Knee protecting airbag device

ABSTRACT

A knee protecting airbag device comprises an airbag, an inflator, and a case housing the airbag and the inflator and arranged in front of a passenger. When the airbag extends and expands, it protrudes toward the rear of the vehicle from the opening of the case, to protect the knees of the passenger. The knee protecting airbag device further comprises a holding member having a mounting portion for mounting the knee protecting airbag device on the vehicle. The holding member holds the case. In the holding member, there are formed a communication hole and a support face arranged on the periphery of the communication hole. The communicating hole communicates with the opening of the case and allows the airbag extending and expanding to protrude therethrough. The support face can support the vehicle front side face of the extending and expanding airbag.

[0001] The present application claims priority to Japanese patent application of Takimoto et al., filed May 21, 2001, No.2001-150478, and Japanese patent application of Takimoto et al., filed May 21, 2001, No.2001-150484, and Japanese patent application of Totani et al., filed May 21, 2001, No.2001-151516, and Japanese patent application of Mizuno et al., filed Dec. 21, 2001, No.2001-390263, and Japanese patent application of Totani et al., filed Jan. 23, 2002, No.2002-14616, the entirely of each is hereby incorporated into the present application by this reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a knee protecting airbag device capable of protecting the knees of a passenger with an airbag to extend and expand when fed with an inflating gas.

[0004] 2. Description of Related Art

[0005] In the prior art, a device for protecting the knees of a passenger is exemplified by an airbag device having a construction, as disclosed in Unexamined Published Japanese Patent Application No. 9-123862. This airbag device is arranged at a position below a steering column so as to protect the knees of a driver. Moreover, this airbag device comprises an airbag, an inflator for feeding an inflating gas to the airbag, a case for housing the airbag and the inflator, and an airbag cover for covering the housed airbag and also allowing that airbag to protrude. The airbag extends and expands, when activated, toward the lower face of the upper portion of a column cover.

[0006] In the airbag device thus constructed, a strong reaction pushing the case forward is applied to the case when the airbag extends and expands with the inflating gas from the inflator. Therefore, the case has to be mounted and fixed on a highly rigid structural member in a vehicle such as a steering column so that the case may not be moved by the reaction.

[0007] At positions below the steering column where the airbag device of the aforementioned construction is arranged, however, there are usually arranged not only the steering column but also a tilt mechanism, a telescopic mechanism, a parking brake device and so on, thereby leaving just a narrow space for arranging the airbag device. Therefore, working space for mounting and fixing the case on the steering column is so narrow that the mounting work requires a long time.

[0008] In order to protect the knees of a passenger seated on the front seat next to the driver's (or a passenger's seat), on the other hand, it is conceivable to arrange the knee protecting airbag device in front of this seat. In front of the passenger's seat where such an airbag device would be installed, however, there are closely arranged a main airbag device for this seat having an airbag for extending and expanding between the windshield and the passenger to protect the passenger, the duct of an air conditioner, and a glove box and so on. Therefore, the working space for arranging this airbag device is narrow as in the case of the driver's seat, and the working space for mounting and fixing the case is narrow.

[0009] In the airbag device thus constructed, moreover, it is also conceivable to arrange a case or the like on a plate-shaped holding member such as a knee panel (or a knee bolster) to be arranged in front of the seated passenger.

[0010] Here, the knee panel is connected to a movement energy absorber arranged on the vehicle front side thereof, thereby facing a large portion the front side of the seated passenger. Moreover, this knee panel receives the forward moving knees of the passenger at the time of a front collision of the vehicle, and moves together with the knees forward, thereby to deform the kinetic energy absorber arranged in front. In short, the knee panel acts to damp the shock on the knees of the passenger moving forward.

[0011] When the airbag and the inflator are to be housed in the plate-shaped holding member or such knee panel, moreover, the airbag cover for covering the folded airbag also has to be mounted on the holding member.

[0012] This airbag cover is desirably constructed to cover the rear side of the holding member such as the knee panel widely so as not to degrade the appearance design. Moreover, this airbag cover is desirably formed not separately of but integrally with a door portion which covers the folded airbag but is opened when pushed by the expanding airbag. In this construction, therefore, the door portion is formed integrally with the rest of the airbag cover itself by providing a breakaway in its periphery.

[0013] When the airbag cover having the integrated door portion is mounted on the aforementioned holding member, however, there arises a problem in that the breakaway portion is smoothly broken to open the door portion.

[0014] In the airbag device thus constructed, moreover, the airbag module including the airbag, the inflator, the case and the airbag cover is mounted and fixed on the vehicle body by supporting it on a mounted bracket.

[0015] When the airbag which has completed its extension and expansion cannot completely absorb the kinetic energy of the knees, moreover, the aforementioned the mounted bracket of the airbag device is constructed to deform and buckle plastically, thereby to absorb the kinetic energy of the knees.

[0016] In short, the airbag device is constructed to absorb the kinetic energy of the knees by buckling the mounted bracket. For this, the mounted bracket has a structure in which it is extended generally forward from the airbag module and is fixed at a predetermined portion of the vehicle body. As a result, the extension of the mounted bracket to the forward needs some degree of length.

[0017] In case the distance between the airbag module and the portion of the vehicle body for rigidly fixing the module is short, therefore, the structure having the aforementioned mounted bracket is not acceptable, and so the conventional device has a low degree of freedom for mounting on the vehicle.

[0018] In case the airbag device of the aforementioned construction is mounted on the vehicle, moreover, the distance from the steering column cover or the instrument panel to the knees of the passenger is usually set short when the passenger is seated. Especially in the case of the driver, this driver frequently depresses the brake pedal at the acting time of the airbag device so that the distance from the column cover to the driver's knees becomes shorter. Therefore, the airbag has to quickly expand in order for it to protect the knees properly.

[0019] In case the airbag device of this kind is arranged at the driver's seat, moreover, the steering column, the tilt mechanism, the telescopic mechanism, the parking brake and so on are closely arranged near the portion where the airbag device is arranged. Therefore, it is difficult to retain a large housing space for arranging the knee protecting airbag device. Especially in recent years, the width of the airbag device in the directions perpendicular to the axis of the case is hard to retain when a glove box or the like is arranged below the column cover. It is, therefore, desired to make the airbag device compact by making the width as small in the directions perpendicular to the case axis as possible.

SUMMARY OF THE INVENTION

[0020] A first object of the invention is to provide a knee protecting airbag device which can be easily mounted on a vehicle.

[0021] Moreover, a second object of the invention is to provide a knee protecting airbag device, in which a door portion can be pushed and smoothly opened even if an airbag cover having the door portion integrated is mounted on a plate-shaped holding member arranged in front of the knees of a seated passenger.

[0022] Moreover, a third object of the invention is to provide a knee protecting airbag device which can absorb the kinetic energy of the knees, even if not fully absorbed by the airbag, and which can improve the degree of freedom of position for mounting.

[0023] Still moreover, a fourth object of the invention is to provide a knee protecting airbag device which can extend the airbag quickly enough to protect the knees of the passenger properly.

[0024] Still moreover, a fifth object of the invention is to provide a knee protecting airbag device which is reduced in width in the directions perpendicular to the axis of a case so that it can be arranged in a narrow housing space.

[0025] The first object of the invention can be achieved by a knee protecting airbag device having the following construction.

[0026] A knee protecting airbag device which comprises a folded airbag, an inflator for feeding an inflating gas to the airbag, and a case housing the airbag and the inflator and arranged on the vehicle in front of a seated passenger. The airbag fed with the inflating gas extends and expands, while protruding backward from the opening of the case, to protect the knees of the passenger. The knee protecting airbag device further comprises a holding member holding the case, which has a mounting portion mounting on the vehicle. And, the holding member includes a communication hole communicating with the opening of the case for allowing the expanding airbag to protrude, and a support face arranged on the periphery of the communication hole for supporting the vehicle front side face of the extending and expanding airbag.

[0027] In this knee protecting airbag device, the case housing the folded airbag and the inflator is held by the holding member. By using the mounting portion formed at the holding member, moreover, the knee protecting airbag device is mounted on the vehicle. At the time of mounting the knee protecting airbag device on the vehicle, therefore, the mounting portion of the holding member holding the case is mounted and fixed on the highly rigid mounting portion of the vehicle body, so that the knee protecting airbag device can be mounted on the vehicle. At this time, the work to mount the mounting portion of the holding member on the mounting portion of the vehicle body can be done in the free space provided both transversely and vertically from the pre-arranged position of the case. By setting the position of the mounting portions of the holding members at a portion where the working space can be easily retained, therefore, the work to mount the knee protecting airbag device on the vehicle can be done more easily than when the case is mounted and fixed directly on the mounting portion of the vehicle body.

[0028] Of course, the holding member holding the case is mounted on the highly rigid mounting portion of the vehicle body so that the case housing the airbag and the inflator is also stably held.

[0029] In the knee protecting airbag device thus constructed, moreover, the vehicle front side face of the airbag extended and expanded is supported by the support face of the holding member. Even when the airbag having extended and expanded interferes with the knees of the passenger, therefore, the airbag does not move forward but can protect the knees of the passenger properly and stably.

[0030] In the knee protecting airbag device thus constructed, therefore, the stable support of the case and the airbag having extended and expanded can be retained and also the mounting the knee protecting airbag device on the vehicle can be facilitated.

[0031] In the knee protecting airbag device thus constructed, moreover, it is preferred that the case housing the folded airbag and the inflator is assembled in advance with the holding member into one assembly.

[0032] With this construction of the knee protecting airbag device, the airbag, the inflator, the case and the holding member can be transported and stored in the assembled state. Therefore, it is easy to handle these members when mounting them on the vehicle.

[0033] Moreover, a second object of the invention can be achieved by a knee protecting airbag device having the following construction.

[0034] In a knee protecting airbag device, a knee protecting folded airbag and an inflator for feeding an inflating gas to the airbag are housed in a plate-shaped holding member arranged in front of the knees of a seated passenger. An airbag cover for covering the housed airbag but allowing it to protrude when activated is mounted on the holding member. The holding member includes a bottomed box-shaped housing portion for housing the airbag and the inflator. The housing portion has its opening facing the rear. The airbag cover includes a door portion, a breakaway portion, a hinge portion, and a general portion. The door portion covers the opening of the housing portion for opening when pushed by the expanding airbag. The thinned breakaway portion is arranged periphery of the door portion broken for the door portion to open. The hinge portion is arranged at one side of the door portion for providing a pivot for the door portion to open. The general portion is arranged around the door portion with the breakaway portion and the hinge portion between them, for covering the periphery of the housing portion of the holding member on the vehicle rear side. Mounting members to be mounted at the housing portion are arranged at a plurality of portions of the general portion in the vicinity of the periphery of opening of the housing portion.

[0035] In the knee protecting airbag device thus constructed, the airbag expands with the inflating gas when discharged by the inflator. Then, the airbag pushes the door portion of the airbag cover and breaks the breakaway portion so that it opens the door portion pivoting at the hinge portion. As a result, the airbag protrudes from the housing portion to the vehicle rear side so that it extends and expands greatly to protect the knees of the passenger.

[0036] In the knee protecting airbag device thus constructed, moreover, the airbag cover is mounted at a plurality of mounting members in the general portion near the periphery of the housing portion opening, on the housing portion through the holding member. At the extending and expanding time of the airbag, therefore, the breakaway portion and the hinge portion of the general portion near the opening periphery of the housing portion are hard to move relative to the housing portion. As a result, the pushing force of the airbag acts properly on the breakaway portion to break the breakaway portion smoothly. Moreover, the hinge portion which pivots when the opening is also hard to move relative to the housing portion and can stabilize the opening action of the door portion. Even if the airbag cover is made of a synthetic resin such as a thermoplastic elastomer, therefore, the door portion is smoothly opened when pushed by the airbag.

[0037] In the knee protecting airbag device thus constructed, therefore, the door portion can be smoothly opened by the push of the airbag, even when on the airbag cover having the integrated door portion is mounted on the holding member arranged in front of the knees of the seated passenger.

[0038] Moreover, the individual mounting members of the airbag cover are only inserted in the holding member around the opening of the housing portion so that the holding member is not reduced in its external surface area. Even if the knees of the passenger interfere the holding member in an unexpanded state of the airbag, therefore, the holding member can catch the knees over a wide area. According to this mode, the holding member can support the front side of the airbag which has completed its expansion, so that the airbag which has completed its extension and expansion is stably supported by the holding member.

[0039] In the knee protecting airbag device thus constructed, moreover, the airbag and the inflator are housed in the housing portion mounted on the holding member, and the airbag cover is mounted on the holding member. This airbag cover is provided with the door portion for covering the folded airbag, and the general portion for covering the rear side of the holding member at the periphery of the housing portion opening. In short, the airbag, the inflator, the airbag cover and the holding member can be assembled in advance. When the airbag, the inflator, the airbag cover and the holding member are assembled in advance, therefore, the airbag and so on can be transported and stored in the assembled state. Therefore, it is easy to handle the individual members while they are mounted on the vehicle.

[0040] In the knee protecting airbag device thus constructed, moreover, it is preferred that the individual mounting members of the airbag cover have retaining holes. The housing portion has a plurality of hooks to be inserted into the retaining holes for retaining the mounting members.

[0041] With the knee protecting airbag device being thus constructed, the work to mount the mounting members on the housing portion can be completed by inserting the individual hooks of the housing portion into the retaining holes of the individual mounting members of the airbag cover and by retaining the mounting members by the individual hooks. It is, therefore, possible to reduce the number of steps of and the cost of mounting the airbag cover on the holding member.

[0042] In the knee protecting airbag device thus constructed, moreover, it is preferred that the holding member comprises joining portions connected to the vehicle body side which are joined when the knee protecting airbag device is mounted on the vehicle. A kinetic energy absorbing member capable of absorbing the kinetic energy of the knees is arranged on the body side of the vehicle at the positions where the joining portions are connected.

[0043] With the knee protecting airbag device being thus constructed, the kinetic energy absorbing member is deformed in absorbing the kinetic energy of the knees if the expanded airbag fails to absorb the kinetic energy of the knees fully. Therefore, the knees of the passenger can be properly protected by lessening the impact on the knees.

[0044] Moreover, the third object of the invention can be achieved by a knee protecting airbag device having the following construction.

[0045] A knee protecting airbag device comprises an airbag module arranged in front of the knees of a seated passenger. The airbag module includes a knee protecting folded airbag, an inflator capable of feeding an inflating gas to the airbag, a case for housing the airbag and the inflator, and an airbag cover for covering the rear-facing opening of the case. The case has an opening for allowing the airbag at the extending and expanding time to protrude toward the rear of the vehicle. The knee protecting airbag device further includes a plate-shaped holding member made of a deformable material. The holding member has a plate-shaped portion extending around the opening of the case, and a mounting portion to be mounted on the vehicle body. The plate-shaped portion is arranged on the vehicle front side of the area of the airbag which has completed its expansion. The mounting portion is arranged near the periphery of the plate-shaped portion. The holding member is constructed to hold the case having housed the airbag and the inflator, and the airbag cover. Then, when a kinetic energy higher than a predetermined level is applied by the knees to the airbag, the plate-shaped portion is deformed to absorb the kinetic energy of the knees.

[0046] With the knee protecting airbag device being thus constructed, the plate-shaped portion of the holding member is deformed to absorb the excess kinetic energy of the knees, if the airbag completely expanded is flattened and the kinetic energy still has not been completely absorbed.

[0047] The plate-shaped portion of the holding member is so extended from the periphery of the opening of the case that it is arranged on the vehicle front side in the area of the airbag which has completed its expansion. Therefore, the plate-shaped portion of the holding member can absorb the kinetic energy of the knees properly through the airbag which has completed its expansion.

[0048] Here, the plate-shaped portion of the holding member is so extended from the periphery of the opening of the case that it covers the vehicle front side in the area of the airbag which has completed its expansion. In this way, the plate-shaped portion is arranged in a large flat area in the vertical and transverse directions of the vehicle. Even with a small deformation stroke at the time of absorbing the kinetic energy, therefore, the kinetic energy of the knees can be sufficiently absorbed by the plate-shaped portion of the holding member.

[0049] Moreover, the holding member is fixed at mounting portions near the periphery of the plate-shaped portion to the vehicle body so that the mounting portions may not obstruct the deformation of the plate-shaped portion.

[0050] Moreover, the plate-shaped portion of the holding member does not extend in the longitudinal direction of the vehicle as does the mounting bracket of the prior art. Specifically, the plate-shaped portion of the holding member is so extended from the periphery of the opening of the case and arranged flatly in the vertical and transverse directions of the vehicle that it may be arranged on the vehicle front side in the area of the airbag which has completed its expansion. Therefore, the airbag module can be easily arranged even if less space is left on the vehicle front side of the airbag module.

[0051] Moreover, the mounting portion of the holding member need not be extended longitudinally from the periphery of the plate-shaped portion. If the airbag module can be mounted and fixed at a predetermined portion of the vehicle body, it can extend transversely from the periphery of the plate-shaped portion. In this case, the size of the airbag device in the longitudinal directions of the vehicle can be made shorter and more compact to improve the degree of freedom for mounting on the vehicle better.

[0052] In the knee protecting airbag device thus constructed, therefore, it is possible to absorb the kinetic energy of the knees, even if it is not fully absorbed by the airbag, and to improve the degree of freedom for mounting on the vehicle.

[0053] In the knee protecting airbag device thus constructed, moreover, it is preferred that the plate-shaped portion of the holding member has ribs capable of adjusting the quantity of the kinetic energy of the knees which can be absorbed.

[0054] In the knee protecting airbag device thus constructed, moreover, it is preferred that the plate-shaped portion of the holding member has a flange portion arranged on its periphery for adjusting the quantity of the kinetic energy of the knees which can be absorbed.

[0055] As in the construction thus far described, the ribs capable of adjusting the absorption quantity of the kinetic energy of the knees are arranged on the plate-shaped portion of the holding member, or the flange portion capable of adjusting the absorption quantity of the kinetic energy of the knees is arranged on the periphery of the plate-shaped portion. Then, the absorption quantity of the kinetic energy can be easily adjusted to correspond to the deformation stroke or the like of the plate-shaped portion by setting the number, shape and arranged position of those rib and flange portions.

[0056] Moreover, the fourth object of the invention can be achieved by a knee protecting airbag device having the following construction.

[0057] A knee protecting airbag device is arranged in front of the knees of a seated passenger. The knee protecting airbag device comprises a knee protecting folded airbag, an inflator for feeding an inflating gas to the airbag, a case opening toward the rear of the vehicle for housing the airbag and the inflator, and an airbag cover for covering the case on its rear-facing side. The airbag cover is formed of an integral molding, including a door portion for covering the opening of the case and a general portion arranged around the door portion. The door portion includes a hinge portion arranged at the lower edge for providing a pivot when the door portion is opened, and a thinned breakaway portion arranged at the periphery excepting the hinge portion. The door portion can be opened downward when the airbag extends and expands. Extension promoting means for quickly opening the door portion to promote the extension and expansion of the airbag is arranged near the door portion.

[0058] With the knee protecting airbag device being thus constructed, the door portion can be quickly opened by the extension promoting means at the beginning of the expansion of the airbag. As a result, the airbag can be quickly protruded to extend and expand from the opening of the door portion opened quickly. In the knee protecting airbag device thus constructed, moreover, the door portion is opened downward with the opening being widest at the upper edge. In other words, the airbag protruding to extend and expand from the case can easily protrude upward from the opening portion of the upper end side of the door portion of the largest opening side. By the opening action of the door portion, therefore, the airbag can be guided upward. As a result, the airbag can extend and expand quickly upward.

[0059] In the knee protecting airbag device thus constructed, therefore, the airbag can be quickly extended to protect the knees of the passenger properly.

[0060] In the knee protecting airbag device thus constructed, moreover, the airbag cover is formed by an integral molding including the door portion having the breakaway periphery, and the general portion around the door portion. Therefore, the door portion is not disharmonious with the surrounding general portion but provides an excellent design.

[0061] In the knee protecting airbag device thus constructed, moreover, it is preferred that the door portion is arranged at such an inclination as to intersect the vertical directions so that its upper edge is more toward the rear and its hinge portion is more toward the front.

[0062] In the knee protecting airbag device thus constructed, even if the upper edge of the door portion, the side that opens first, is arranged toward the vehicle rear and removed from the housed airbag and inflator, the extension promoting means is arranged near the door portion so that the door portion can be quickly opened. Therefore, the airbag can quickly extend and expand. With the knee protecting airbag device being thus constructed, moreover, the lower side of the door portion in the airbag cover can be arranged toward the front so that the space in front of the knee or lower portion of the passenger can be kept wide. Therefore, the airbag device can be mounted on the vehicle without bumping the toes or the like of the passenger.

[0063] In the knee protecting airbag device thus constructed, moreover, it is preferred that the case includes a peripheral wall portion and a bottom wall portion. The airbag cover has mounting wall portions for mounting and fixing the airbag cover on the case peripheral wall portion. The mounting wall portions to serve as the extension promoting means are arranged near an upper end breakaway portion arranged on the upper end side of the door portion.

[0064] With the knee protecting airbag device thus constructed, the portion near the upper end breakaway portion is firmly connected to the case by the mounting wall portions serving as the extension promoting means. In other words, with the protrusion of the airbag, the portion near the upper end breakaway portion is not moved away from the case by the push of the airbag. By the airbag, therefore, the upper end breakaway portion on the upper edge, where the opening of the door portion starts, can be smoothly broken so that the remaining breakaway portions can also be smoothly broken. As a result, the door portion can be quickly opened so that the airbag can quickly protrude to extend and expand from the opening of the door portion opened.

[0065] In the knee protecting airbag device thus constructed, moreover, it is preferred that a guide wall portion for covering the lower area of the opening is arranged on the case near the door portion. The guide wall portion can serve as the extension promoting means to guide the expanding airbag toward the upper side of the door portion.

[0066] In case the knee protecting airbag device is thus constructed, the airbag to extend and expand when fed with the inflating gas is guided toward the upper side of the door portion by the guide wall portion serving as extension promoting means. At the beginning of the extension of the airbag, therefore, the breakaway portion arranged on the upper edge of the door portion can be broken to open the downward-opening door portion smoothly from the upper edge. As a result, the door portion can be quickly opened so that the airbag can quickly protrude to extend and expand from the opening of the door portion opened.

[0067] In the knee protecting airbag device thus constructed, moreover, it is possible that the door portion has ribs formed to protrude forward. The face of each rib facing the front is a face to receive a push, serving as the extension promoting means for opening the door portion when pushed by the airbag expanding.

[0068] In case the knee protecting airbag device is thus constructed, at the beginning of the expansion of the airbag, the protruding airbag pushes the front face of the rib backward to open the door portion. Usually in the case of the knee protecting airbag device constructed with no rib arranged on the door portion, the protruding airbag pushes the front side face of the door portion to open the door portion. In case the knee protecting airbag device is constructed with ribs, more specifically, the rib shortens the distance between the airbag and the door portion substantially. As compared with the case of no rib, therefore, the door portion can be quickly opened. As a result, the airbag can quickly protrude to extend and expand out from the opening of the door portion opened quickly.

[0069] In the knee protecting airbag device thus constructed, moreover, it is possible that the case includes a peripheral wall portion and a bottom wall portion. A left side wall portion and a right side wall portion to be arranged transversely of the vehicle in the case peripheral wall portion are inclined as is diametrically upward apart from each other. The left side wall portion and the right side wall portion act as the extension promoting means.

[0070] In case the knee protecting airbag device is thus constructed, the inflating gas discharged from the inflator is guided upward in the airbag by the left side wall portion and the right side wall portion. In other words, the airbag expanding when fed with the inflating gas from the inflator can be guided toward the upper side of the door portion. By the protruding airbag, therefore, the downward door portion can be smoothly opened from the upper end side. As a result, the airbag can be quickly protruded to extend and expand from the opening of the door portion opened quickly.

[0071] Moreover, the fifth object of the invention can be achieved by a knee protecting airbag device having the following construction.

[0072] A knee protecting airbag device comprises a folded airbag, an inflator for feeding an inflating gas to the airbag, and a case housing the airbag and the inflator and arranged below a steering column. The airbag fed with the inflating gas extends and expands while protruding to vehicle rear side from the opening of the case, to protect the knees of the passenger. The case is opened toward the vehicle rear and includes a peripheral wall portion and also a bottom wall portion closing the vehicle front side of the peripheral wall portion. The inflator is of a cylinder type and is so housed in the case that its axis is arranged generally parallel to the axial direction of the peripheral wall portion.

[0073] In the knee protecting airbag device thus constructed, the cylinder type inflator is arranged such that its axis is generally parallel to the axial direction of the case peripheral wall portion. Moreover, the cylinder type inflator is made longer in the axial length than the external diameter. If the inflator is so arranged in the case that its axis is generally parallel to the axial direction of the case peripheral wall portion, therefore, the width in the directions perpendicular to the axis of the case may be set to the sum of the external diameter of the inflator and the size of the space which can house the folded airbag. As a result, the width of the directions perpendicular to the axis of the case can be made smaller than that of the case in which the cylinder type inflator is arranged with its axial direction being generally perpendicular to the axial direction of the case.

[0074] In the knee protecting airbag device thus constructed, therefore, the case can be reduced in the width perpendicular to the axial direction and thus can be arranged in a narrow housing space.

[0075] Moreover, it is possible that the inflator is of a disc type and is so mounted and fixed on the peripheral wall portion of the case that its axis is generally perpendicular to the axial direction of the peripheral wall portion.

[0076] In the knee protecting airbag device thus constructed, the disc type inflator is so mounted and fixed on the peripheral wall portion of the case that its axis is generally perpendicular to the axial direction of the case peripheral wall portion. Moreover, the disc type inflator is made larger in its external diameter than in the axial length. If the inflator is mounted and fixed on the peripheral wall portion of the case so that its axis is generally perpendicular to the axial direction of the case peripheral wall portion, the distance from the wall portion on which the inflator is mounted to the wall portion confronting the inflator may be set to be the sum of the axial length of the inflator and the size of the space which can house the folded airbag. If the inflator is fixed on the wall portion positioned in the vertical directions of the peripheral wall portion portion, for example, the width in the vertical direction perpendicular to the axis of the case can be reduced. If the inflator is fixed on the wall portion positioned in the transverse directions of the peripheral wall portion, on the other hand, the width in the transverse directions perpendicular to the axis of the case peripheral wall portion can also be reduced. As a result, the width in the directions perpendicular to the axis of the case can be made smaller than that of the case in which the inflator is mounted and fixed on the bottom wall portion of the case.

[0077] In the knee protecting airbag device thus constructed, therefore, the size of the case can be reduced in a direction perpendicular to the axis and arranged in the narrow housing space.

[0078] In the knee protecting airbag device thus constructed, moreover, it is preferred that the case is constructed such that the upper end side of the open face is positioned closer to the vehicle rear side than the lower end side of the open face. The inflator is mounted and fixed on the upper side wall portion in the peripheral wall portion.

[0079] In the knee protecting airbag device thus constructed, the inflator is mounted and fixed on the upper side wall in the case in which the upper edge of the opening face is positioned close to the vehicle rear. Moreover, the upper side wall portion of the case can be set to be a larger length in the longitudinal directions to the extent in which the rear edge is positioned on the vehicle rear side relative to that of the remaining peripheral wall portion of the case. Therefore, the depth of the case can be made smaller than that of the case in which the inflator is mounted and fixed on the remaining peripheral wall portion.

[0080] Moreover, it is possible that the inflator has a gas feed passage for feeding the inflating gas to the airbag folded and housed in the case and is arranged outside of the case.

[0081] In the knee protecting airbag device thus constructed, the inflator is not arranged in the case, and only the folded airbag and the gas feed passage for feeding the inflating gas to the airbag are arranged in the case. This gas feed passage needs no gas producing mechanism so that it can have a smaller volume than that of the inflator. Therefore, the width in one direction perpendicular to the axis of the case can be made smaller than that of the airbag device in which the inflator is arranged in the case.

[0082] Therefore, the knee protecting airbag device thus constructed can have a smaller width in one direction perpendicular to the axis and can be arranged in a narrow housing space.

BRIEF DESCRIPTION OF THE DRAWINGS

[0083]FIG. 1 is a schematic vertical section showing the operation of a knee protecting airbag device according to a first embodiment of the present invention in the longitudinal directions of a vehicle;

[0084]FIG. 2 is a schematic vertical section of the knee protecting airbag device of the first embodiment in the longitudinal directions of the vehicle;

[0085]FIG. 3 is a section of a portion III-III of FIG. 2;

[0086]FIG. 4 is a schematic front elevation showing the operation of the knee protecting airbag device of the first embodiment and taken from the rear side of the vehicle;

[0087]FIG. 5 is a front elevation of an airbag to be used in the first embodiment;

[0088]FIG. 6 is a schematic section of a portion VI-VI of FIG. 5;

[0089]FIGS. 7A to 7E are schematic views showing how to fold the airbag used in the first embodiment;

[0090]FIGS. 8A and 8B are schematic vertical sections for explaining the state of the knee protecting airbag device of the first embodiment during extending and expanding of the airbag in the longitudinal directions of the vehicle;

[0091]FIGS. 9A and 9B are schematic lateral sections showing the state of the knee protecting airbag device of the first embodiment during extending and expanding of the airbag in the longitudinal directions of the vehicle;

[0092]FIGS. 10A and 10B are schematic front elevations taken from the vehicle rear side for explaining the extension and expansion of the airbag in the knee protecting airbag device of the first embodiment;

[0093]FIG. 11 is a schematic vertical section showing the state in which the airbag has completed its extension and expansion in the knee protecting airbag device according to the first embodiment in the longitudinal directions of the vehicle;

[0094]FIG. 12 is a schematic vertical section of a knee protecting airbag device according to a second embodiment of the invention in the longitudinal directions of the vehicle;

[0095]FIG. 13 is a schematic front elevation showing the operation of the knee protecting airbag device of the second embodiment and taken from the vehicle rear side;

[0096]FIG. 14 is a schematic vertical section of a knee protecting airbag device according to a third embodiment of the invention in the longitudinal directions of the vehicle;

[0097]FIG. 15 is a schematic front elevation showing the operation of the knee protecting airbag device of the third embodiment and taken from the vehicle rear side;

[0098]FIG. 16 is a schematic front elevation taken from the vehicle rear side and showing the state in which the knee protecting airbag device of the first embodiment is arranged in front of a passenger's seat;

[0099]FIG. 17 is a schematic vertical section showing the operation of a knee protecting airbag device according to a fourth embodiment of the invention in the longitudinal directions of the vehicle;

[0100]FIG. 18 is a schematic vertical section of the knee protecting airbag device of the fourth embodiment in the longitudinal directions of the vehicle;

[0101]FIG. 19 is a section of a portion XIX-XIX of FIG. 18;

[0102]FIG. 20 is a schematic front elevation showing the operation of the knee protecting airbag device of the fourth embodiment and taken from the vehicle rear side;

[0103]FIG. 21 is an exploded front side perspective view of a knee panel to be used as a holding member and an airbag cover in the fourth embodiment;

[0104]FIG. 22 is an exploded rear side perspective view of the knee panel to be used as the holding member and the airbag cover in the fourth embodiment;

[0105]FIG. 23 is a front elevation of the airbag to be used in the fourth embodiment;

[0106]FIG. 24 is a schematic section of a portion XXIV-XXIV of FIG. 23;

[0107]FIG. 25 is a view showing the state in which the airbag cover used in the fourth embodiment is mounted on the knee panel as the holding member;

[0108]FIG. 26 is a view showing the state, in which the airbag cover used in the fourth embodiment is mounted on the knee panel as the holding member, and the state after FIG. 25;

[0109]FIG. 27 is a schematic front elevation taken from the vehicle rear side for explaining the extension and expansion of the airbag in the knee protecting airbag device of the fourth embodiment;

[0110]FIG. 28 is a schematic vertical section taken in the vehicle longitudinal directions and showing the state in which the airbag has completed its extension and expansion in the knee protecting airbag device of the fourth embodiment;

[0111]FIG. 29 is a schematic front elevation taken from the vehicle rear side and showing the state in which the knee protecting airbag device of the fourth embodiment is arranged on the vehicle front side of the passenger's seat;

[0112]FIG. 30 is a schematic vertical section taken in the longitudinal directions and showing the operation of a knee protecting airbag device according to a fifth embodiment of the invention;

[0113]FIG. 31 is a schematic vertical section of the knee protecting airbag device of the fifth embodiment in the longitudinal directions of the vehicle;

[0114]FIG. 32 is a schematic section of a portion XXXII-XXXII of FIG. 31;

[0115]FIG. 33 is a schematic front elevation taken from the vehicle rear side and showing the operation of the knee protecting airbag device of the fifth embodiment;

[0116]FIG. 34 is an exploded perspective front side view of a knee panel to be used as a holding member and an airbag cover in the fifth embodiment;

[0117]FIG. 35 is an exploded perspective rear side view of a knee panel to be used as the holding member and an airbag cover in the fifth embodiment;

[0118]FIG. 36 is a view showing the state in which the airbag cover used in the fifth embodiment is mounted on the knee panel as the holding member;

[0119]FIGS. 37A and 37B are explanatory views for explaining the deformed state of the plate portion of the knee panel as the holding member used in the fifth embodiment;

[0120]FIG. 38 is a schematic vertical section showing the operation of the knee protecting airbag device according to a sixth embodiment of the invention and taken in the longitudinal directions of the vehicle;

[0121]FIG. 39 is a schematic vertical section of the knee protecting airbag device of the sixth embodiment in the longitudinal directions of the vehicle;

[0122]FIG. 40 is a sectional view of a portion taken along XL-XL of FIG. 39;

[0123]FIG. 41 is a schematic front elevation showing the operation of the knee protecting airbag device of the sixth embodiment and taken from the vehicle rear side;

[0124]FIG. 42 is a schematic vertical section of a knee protecting airbag device according to a seventh embodiment of the invention in the longitudinal directions of the vehicle;

[0125]FIG. 43 is a section of a portion taken along XLIII-XLIII of FIG. 42;

[0126]FIG. 44 is a schematic front elevation taken from the vehicle rear side and showing the operation of a knee protecting airbag device according to an eighth embodiment of the invention;

[0127]FIG. 45 is a schematic front elevation taken from the vehicle rear side and showing the state in which the knee protecting airbag device of the sixth embodiment is arranged in front of the passenger's seat;

[0128]FIG. 46 is a schematic vertical section showing the operation of a knee protecting airbag device according to an ninth embodiment of the invention in the longitudinal directions of the vehicle;

[0129]FIG. 47 is a schematic vertical section of the knee protecting airbag device of the ninth embodiment in the longitudinal directions of the vehicle;

[0130]FIG. 48 is a section of a portion taken along XLVIII-XLVIII of FIG. 47;

[0131]FIG. 49 is a schematic front elevation taken from the vehicle rear side and showing the operation of the knee protecting airbag device of the ninth embodiment;

[0132]FIG. 50 is a front elevation of an airbag used in the ninth embodiment;

[0133]FIG. 51 is a schematic section of a portion taken along LI-LI of FIG. 50;

[0134]FIG. 52 is a schematic vertical section of a knee protecting airbag device according to a tenth embodiment of the invention in the longitudinal directions of the vehicle;

[0135]FIG. 53 is a front elevation, as taken in a direction LIII of FIG. 52, of the knee protecting airbag device of the tenth embodiment;

[0136]FIG. 54 is a section taken along LIV-LIV of FIG. 53;

[0137]FIG. 55 is a front elevation of an airbag used in the tenth embodiment;

[0138]FIG. 56 is a schematic section of a portion along LVI-LVI of FIG. 55;

[0139]FIG. 57 is a schematic view of a knee protecting airbag device according to an eleventh embodiment of the invention;

[0140]FIG. 58 is a schematic vertical section of the knee protecting airbag device of the eleventh embodiment in the longitudinal directions of the vehicle;

[0141]FIG. 59 is a section of a portion taken along LIX-LIX of FIG. 58;

[0142]FIG. 60 is a schematic view of a knee protecting airbag device according to a twelfth embodiment of the invention;

[0143]FIG. 61 is a schematic vertical section of the knee protecting airbag device of the twelfth embodiment in the longitudinal directions of the vehicle; and

[0144]FIG. 62 is a section of a portion taken along LXII-LXII of FIG. 61.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0145] The invention will be described below by way of embodiments shown in the drawings. In addition, the invention is not limited to the embodiments. All modifications within the requirements of the claims and equivalents with respect to the requirements should be included in the scope of the claims.

[0146] Embodiments of the present invention will be described with reference to the accompanying drawings.

[0147] First of all, here will be the described knee protecting airbag devices S1 to S3 which can achieve the first object of the invention.

[0148] A knee protecting airbag device S1 according to a first embodiment of the invention is shown in FIGS. 1 to 3.

[0149] Here, the vertical, transverse and longitudinal directions will be termed to correspond to the vertical, transverse and longitudinal directions of a vehicle at the time when the knee protecting airbag device is mounted on the vehicle.

[0150] Moreover, the passenger M is a driver MD, or a person MP who sat on the passenger's seat. That is, the passenger M includes the driver MD.

[0151] The airbag device S1 is so arranged below a steering column 3 on the vehicle front side of a driver MD, one of the passengers M, so as to protect the knees K of the driver MD. The airbag device S1 comprises a folded airbag 26, an inflator 21, a case 19, an airbag cover 13 and a holding member 12. The inflator 21 feed an inflating gas to the airbag 26. The case 19 houses the airbag 26 and the inflator 21. The airbag cover 13 is constructed to cover the airbag 26 folded. The holding member 12 holds the case 19. In the airbag device S1 of the embodiment, the case 19 having the airbag 26 housed therein is held by the holding member 12. At the two left and right ends of the holding member 12, moreover, there are formed mounting portions 12 a and 12 a, which are mounted and fixed on frame portions FC and FR having rigidity of the vehicle, as shown in FIG. 4. Moreover, the folded airbag 26 is arranged in front of the knees K (KL and KR) of the seated driver MD below the steering column 3.

[0152] Here in the case of the embodiment, the frame portion FR is the front body pillar in the body of the vehicle. On the other hand, the frame portion FC is the center brace in the body of the vehicle.

[0153] Moreover, the steering column 3 comprises, as shown in FIG. 1, a main shaft 4 connected to a steering wheel 1, and a column tube 5 enclosing the main shaft 4. Between the main shaft 4 and the column tube 5, there are arranged the not-shown tilt mechanism capable of adjusting the angle of the ring face of the steering wheel, and the not-shown telescopic mechanism capable of moving and stopping the steering wheel 1 in the axial directions of the shaft.

[0154] A column cover 8 is formed of a synthetic resin into a generally square tubular shape or the like. The column cover 8 is constructed to cover the steering column 3 below the steering wheel 1. Moreover, the column cover 8 is arranged in the axial directions of the steering column 3. Specifically, the column cover 8 is inclined upward so that its front side is downward and its rear side is upward. Moreover, the column cover 8 has a lower face 8 a formed into a generally rectangular shape and profile line curving upward.

[0155] The holding member 12 is formed of a sheet metal into a plate shape. The holding member 12 is arranged at a position on the lower side of an instrument panel (hereafter called the “dashboard”) 10, as shown in FIGS. 1 to 4. This holding member 12 is arranged at a position containing the lower side of the column cover 8 enclosing the steering column 3. Moreover, the holding member 12 is inclined upward so as to have its upper end positioned toward the vehicle rear side and its lower end positioned to the front. On the two left and right ends of the holding member 12, there are formed the mounting portions 12 a which are individually provided with the not-shown mounting holes for inserting bolts 41 thereinto. The holding member 12 is connected and fixed by fastening its mounting portions 12 a and 12 a individually on the lefthand and righthand vehicle frame portions FC and FR at a plurality of positions by means of the bolts 41. Moreover, the holding member 12 mounts and fixes the case 19 on its front side face by bolt, nut, rivet and welding means. In the embodiment, the holding member 12 fixes the case 19 (see FIG. 3) by fastening nuts on bolts 17 which protrude forward from the rear face of the holding member 12 through to the forward face.

[0156] In the portion of the holding member 12 for mounting the case 19, there is formed a communication hole 12 b for communicating with the later-described opening 19 e of the case 19. This communication hole 12 b allows the airbag 26 housed in the case 19 to protrude into the vehicle compartment toward the rear of the vehicle. Moreover, the communication hole 12 b is opened into such a generally rectangular shape as to match the opening 19 e of the case 19. The communication hole 12 b has a periphery formed into a flat shape. This periphery of the communication hole 12 b provides a support face 12 c capable of supporting the vehicle front side face of the extending and expanding airbag 26.

[0157] In the case of the embodiment, as shown in FIGS. 1 to 4, the airbag cover 13 is mounted and fixed on the face of the holding member 12 on the vehicle rear side by means such as bolt, nut or rivet. Moreover, the airbag cover 13 performs a role as an interior member to cover the folded airbag 26 and the face of the holding member 12 on the vehicle compartment side. In the case of the embodiment, the airbag cover 13 is fixed on the holding member 12 (as referred to in FIG. 3) by using clips 13 a and an adhesive. In the airbag cover 13, moreover, there is formed a door portion 15 having a generally rectangular plate shape, which is arranged at the position of the communication hole 12 b in the holding member 12. The door portion 15 is opened into the vehicle compartment side when pushed by the extending and expanding airbag 26. Moreover, the door portion 15 has therearound a thin breakaway portion 14 having an inverted U-shape as viewed from the vehicle compartment. And, the door portion 15 has a hinge portion as an integral hinge on the lower edge. When the airbag 26 expands, the door portion 15 is opened at the hinge portion 16 toward the lower side on the vehicle compartment side while being pressed by the airbag 26 to break the breakaway portion 14.

[0158] The case 19 is formed of a sheet metal into a generally rectangular box shape. As shown in FIGS. 1 to 3, the case 19 is arranged as a housing portion for housing the folded airbag 26. In the case of the embodiment, moreover, the case 19 houses the airbag 26 together with the inflator 21. The case 19 is provided with a peripheral wall portion 19 a of a generally rectangular tubular shape, and a bottom wall portion 19 d. The peripheral wall portion 19 a is opened as the opening 19 e on the vehicle rear side. The bottom wall portion 19 d is formed into a generally rectangular shape to close the vehicle front side of the peripheral wall portion 19 a. On the periphery of the opening 19 e in the peripheral wall portion 19 a, there is formed a flange portion 19 b to be connected to the holding member 12. In the upper face of the peripheral wall portion 19 a on the vehicle front side, there are formed a plurality of (e.g., two in the embodiment) mounting holes 19 c for mounting and fixing the inflator 21 and the airbag 26. Moreover, the axis O of the peripheral wall portion 19 a of the case 19 is arranged along the lower face 8 a of the column cover 8 (or in the axial direction of the steering column 3), as shown in FIG. 1.

[0159] As shown in FIGS. 1 to 3, 5 and 6, the inflator 21 comprises a cylindrical body 22 and two brackets 23 and 23. The body 22 can discharge an inflating gas G in response to an electric signal. The body 22 is provided with gas discharge ports 22 a for discharging the inflating gas G. In the case of the embodiment, moreover, the body 22 is activated simultaneously with a not-shown airbag device which is mounted in the steering wheel 1, in response to the electric signal coming from a control device for activating the airbag device. Each bracket 23 comprises a retaining ring 23 a made of a sheet metal, and a bolt 23 b protruding from the retaining ring 23 a. This retaining ring 23 a is mounted on the body 22 by fitting it elastically on the body 22 and by constricting it. The inflator 21 is mounted and fixed together with the airbag 26 in the case 19, as follows. First of all, the inflator 21 is arranged in the airbag 26, and the individual bolts 23 b are protruded from the later-described mounting holes 29 of the airbag 26. Moreover, these bolts 23 b are protruded from the individual mounting holes 19 c of the case 19 and are fastened by nuts 24. Moreover, the not-shown lead wire is connected with the body 22.

[0160] Here, the case 19 may also be integrated with the holding member 12 by the pressing or welding method using a metallic material such as a sheet metal or by the die-casting method using a light metal alloy material of aluminum or the like. In this modification, the flange portion 19 b of the case 19 is made large, and the mounting portions 12 a are formed at the large flange portion 19 b.

[0161] The airbag 26 is formed of a woven fabric having flexibility such as polyester or polyamide. As shown in FIGS. 4 to 6, the airbag 26 is formed to have a generally rectangular plate shape upon completion of the extension and expansion. In the case of the embodiment, the airbag 26 is constructed of two woven fabrics: a wall portion 27 facing the column cover (the vehicle side) in a generally rectangular shape; and a wall portion 28 facing the driver MD (the passenger M) in a generally rectangular shape. Moreover, the airbag 26 is formed by sewing the wall portions 27 and 28 at their periphery. In the lower side of the vehicle side wall portion 27, there are formed the mounting holes 29 for inserting the individual bolts 23 b of the inflator 21 therethrough.

[0162] On the other hand, as shown in FIG. 5, the passenger side wall portion 28 includes a lower central portion 28 b to the rear of the inflator 21. Moreover, the passenger side wall portion 28 comprises a central portion 28 a, and left and right joining portions 28 c and 28 c merging into the central portion 28 a. This central portion 28 a is a portion at the transversely central position of the airbag 26. The joining portions 28 c and 28 c are positioned on the central side of two left and right edges 26 a and 26 b in the airbag 26 being extended flat.

[0163] In the embodiment, moreover, the airbag 26 is provided with a lower expansion portion 30 on the side housing the inflator 21, and an upper expansion portion 31 extending on the upper side of the lower expansion portion 30. This lower expansion portion 30 and upper expansion portion 31 are vertically divided at the arranged position of the later-described tether 32. The lower expansion portion 30 is a portion on the upstream side of the inflating gas G. The lower expansion portion 30 is a portion to protrude during extending and expanding of the airbag 26 backward from the communication hole 12 b formed in the holding member 12. The lower expansion portion 30 covers the rear side of the communication hole 12 b in the holding member 12. Also, the lower expansion portion 30 covers the lower side of the rear-facing side of the support face 12 c arranged on the entire periphery of the communication hole 12 b. Moreover, the lower expansion portion 30 can cover the front sides of the knees K (KL and KR) of the driver MD, too. The upper expansion portion 31 communicates with the lower expansion portion 30 downstream of the inflating gas G. Moreover, the upper expansion portion 31 is a portion protruding upward from the lower expansion portion 30 along the lower face 8 a of the column cover 8. The upper expansion portion 31 covers from the upper side of the rear-facing side of the support face 12 c to the vicinity of the upper end 8 b on the lower face 8 a side of the column cover 8 at least. Here in the case of the embodiment, the lower expansion portion 30 during extending and expanding is set to have a larger transverse width than that of the communication hole 12 b so that it can protect the two knees KL and KR of the driver MD sufficiently.

[0164] In the airbag 26, as shown in FIGS. 5 and 6, there are arranged the tethers 32 and 33 for connecting the vehicle side wall portion 27 and the passenger side wall portion 28. These tethers 32 and 33 set the thickness sizes of the lower expansion portion 30 and the upper expansion portion 31 at the extending and expanding time. Specifically, the tethers 32 and 33 are thickness regulating means for inserting the airbag 26 smoothly into the clearance between the knees K of the driver MD and the column cover lower face 8 a. The tethers 32 and 33 are made of a flexible material like the walls 27 and 28 of the airbag 26. Moreover, the tethers 32 and 33 are sewn to the walls 27 and 28. In the case of the embodiment, the tethers 32 and 33 are arranged generally in the transverse direction above the inflator 21. Further, the individual tethers 32 and 33 are arranged to have their two left and right ends removed from the two left and right edges 26 a and 26 b of the airbag 26. The tether 32 is arranged as the thickness regulating means and performs a role as a gas flow guide member, as will be described in the following. The tether 32 guides the inflating gas G discharged from the inflator 21 to the upper expansion portion 31 while also directing it toward the two left and right edges 26 a and 26 b of the airbag 26.

[0165] In the airbag 26, more specifically, the gas from inflator 21 is blocked above by the tether 32. Gas communication holes 34 and 34 are formed between the left end 32 a of the tether 32 and the airbag left edge 26 a and between the right end 32 b of the tether 32 and the airbag right edge 26 b. When the inflating gas G flows in the airbag upper expansion portion 31 which is downstream, the inflating gas G discharged from the inflator 21 flows in the airbag lower expansion portion 30, which is upstream, upward to the gas communication holes 34 and 34 while being directed leftward and rightward along the tether 32.

[0166] In the airbag 26 of the embodiment, moreover, at the initial stage of the extension and expansion and before the upper expansion portion 31 completes its extension and expansion, the lower expansion portion 30 is so folded as to cover the left and right periphery of the communication hole 12 b. In the case of the embodiment, the airbag 26 is folded through the following vertical folding step and transverse folding step.

[0167] At the vertical folding step, as shown in FIGS. 7A to 7D, the passenger side wall portion 28 is extended flat over the vehicle side wall portion 27, the two left and right edges 26 a and 26 b are vertically folded closer to the central portion 28 a thereby to fold the airbag 26 to such a transverse-width B1 as to house the same in the case 19. This vertical folding step of the airbag 26 is characterized in that the folding portions 37 and 37 on the left and right edge sides of the airbag 26 are respectively arranged on the sides of the vehicle side wall portion 27 at the position of the left and right joining portions 28 c and 28 c of the passenger side wall portion 28. The folded portions 37 and 37 on the two left and right edge sides of the airbag 26 at the vertically folding step can be prepared by folding them into bellows or by rolling the two left and right edges 26 a and 26 b on the side of the vehicle side wall portion 27.

[0168] Moreover, the transverse folding step is done after the vertically folding step. At the transverse folding step, as shown in FIGS. 7D and 7E, the upper edge 26 c of the airbag 26 finished the vertically folding step is transversely folded closer to the side of the arranged position of the inflator 21 to form a folded portion 38 to such a vertical width V1 (see FIG. 2) that the airbag 26 can be housed in the case 19.

[0169] Here will be described how to mount the airbag device S1 on the vehicle. First of all, the airbag 26 is folded while housing the inflator 21. Here, the individual bolts 23 b of the inflator 21 are protruded in advance from the mounting holes 29. Moreover, the not-shown lead wire extending from the body 22 is led out from the not-shown predetermined insert hole in the airbag 26.

[0170] In the case of the embodiment, the airbag 26 is folded through two steps, the vertical folding step and the transverse folding step above described.

[0171] At the vertical folding step, moreover, the passenger side wall portion 28 is extended flat against the vehicle side wall portion 27, as shown in FIG. 7A. Next, as shown in FIG. 7B, the two left and right edges 26 a and 26 b of the airbag 26 are so individually folded toward the side of the vehicle side wall portion 27 as to come closer to the central portion 28 a of the passenger side wall portion 28. As shown in FIG. 7c, moreover, the two left and right folded edges 35 and 36 of the airbag 26 are folded close to the central portion 28 a of the passenger side wall portion 28. At this time, the two edges 35 and 36 are individually folded toward the side of the vehicle side wall portion 27 to form the folded portions 37 and 37. Next, as shown in FIG. 7D, the folded portions 37 and 37 are so folded to complete the vertically folding step that they may be placed on the outer surface (i.e., on the vehicle rear side and on the passenger side) at the central portion 28 a of the passenger side wall portion 28. At this time, the folded portions 37 and 37 are individually arranged on the side of the vehicle side wall portion 27 in the left and right joining positions 28 c and 28 c of the passenger side wall portion 28.

[0172] At the transverse folding step after the vertically folding step, as shown in FIGS. 7D and 7E, the vertically folded airbag 26 is folded by rolling it from the upper edge 26 c toward the vehicle side wall portion 27, to form the folded portion 38. This folded portion 38 is folded to have the vertically housing width V0 (see FIG. 2) of the case 19. Thus, the transversely folding step is completed to complete the folding work of the airbag 26.

[0173] After the airbag 26 was folded up, moreover, it is wrapped with the not-shown breakable wrapping film so that the airbag may not become loose, and the individual bolts 23 b are protruded from the wrapping film. These individual bolts 23 b thus protruded are assembled with spring nuts 40 having a thin sheet shape. Then, the airbag 26 and the inflator 21 are housed in the case 19, and the individual bolts 23 b are protruded from the mounting holes 19 c of the case 19. When the nuts 24 are screwed on the individual protruded bolts 23 b, the inflator 21 and the airbag 26 can be housed and fixed in the case 19. Here, the not-shown lead wire extending from the inflator body 22 is led from the wrapping film and from the not-shown insert hole of the case 19. Then, the flange portion 19 b of the case 19 is fixed on the holding member 12 by means of the bolts 17, and they are assembled to form an airbag assembly SA1.

[0174] After this, the mounting portions 12 a and 12 a formed on the left and right ends of the holding member 12 in the formed airbag assembly SA1 are individually fixed on the vehicle frame portions FC and FR arranged on the left and right sides, by means of the bolts 41. The airbag device S1 can be mounted on the vehicle, as shown in FIGS. 1 to 4, by connecting the not-shown lead wire with the control circuit and by mounting the dashboard 10 and other items on the vehicle.

[0175] After the airbag device S1 is mounted on the vehicle, the inflating gas G is discharged from the gas discharge ports 22 a if the specified electric signal is inputted to the inflator body 22. Then, the airbag 26 is expanded by the inflating gas G to break the not-shown wrapping film and to protrude backward while pushing and opening the door portion 15 of the airbag cover 13. After this, the airbag 26 extends and expands upward along the column cover lower face 8 a while being transversely and vertically unfolded.

[0176] At the initial stage of the extension and expansion of the airbag 26, the lower central portion 28 b confronting the inflator at the central portion 28 a of the passenger side wall portion 28 is pushed by the inflating gas G discharged from the inflator 21, to protrude at first toward the side of the driver MD at the rear HB, as shown in FIGS. 8A, 9A and 10A. At this time, as the lower central portion 28 b protrudes, the folded portions 38, 37 and 37 move to the rear HB of the vehicle to break the breakaway portion 14 and then to open the door portion 15 of the airbag cover 13.

[0177] Simultaneously with this, joining positions 28 d below the joining positions 28 c leading to the lower central portion 28 b also protrudes toward the driver MD side (see FIG. 9A). As the inflating gas G flows in, moreover, the folded portions 37 and 37 near the lower joining position 28 d are unfolded. These folded portions 37 and 37 are individually arranged, when vertically folded, on the side of the vehicle side wall portion 27 of the left and right joining positions 28 c and 28 c of the passenger side wall portion 28. Therefore, the folded portions 37 and 37 near the lower joining position 28 d are suppressed as much as possible from protruding toward the driver MD. As shown in FIGS. 9A and 9B, more specifically, the folded portions 37 and 37 are unfolded leftward HL and rightward HR while being widely extended from the lower joining position 28 d toward the column cover 8 (toward the holding member 12). Then, the airbag lower expansion portion 30 completes the extension and expansion.

[0178] After this, the protrusion of the central portion 28 a of the passenger side wall 28 toward the driver MD proceeds upward VU from the lower central portion 28 b. Simultaneously with this, the folded portions 37 and 37 are unfolded upward VU from the vicinity of the lower joining portion 28 d. As a result, the transversely folded portion 38 extends and expands while being unfolded along the lower face 8 a of the column cover 8. Thus, the airbag upper expansion portion 31 completes its extension and expansion.

[0179] In the embodiment, moreover, the vehicle front-facing side (or the vehicle side wall portion 27) of the extending and expanding airbag 26 is supported, at its portions 27 a, 27 b, 27 c and 27 d extending and expanding vertically and transversely from the communication hole 12 b of the holding member 12, through the airbag cover 13, as shown in FIGS. 8A and 8B to 10A and 10B, by the support face 12 c arranged on the periphery of the communication hole 12 b. Moreover, the support face 12 c supports the door portion 15 which is pushed and opened by the protruding airbag 26, as shown in FIG. 11.

[0180] In the airbag device S1 of the embodiment thus far described, the case 19 housing the folded airbag 26 and the inflator 21 is held by the holding member 12 arranged below the column cover 8. Moreover, the airbag device S1 is mounted on the vehicle by using the mounting portions 12 a and 12 a formed in the holding member 12. Therefore, the airbag device S1 can be mounted on the vehicle when the mounting portions 12 a and 12 a formed on the left and right ends of the holding member 12 holding the case 19 are mounted and fixed on the left and right specified frame portions FC and FR, highly rigid structural members in the vehicle. In the airbag device S1 of the embodiment, moreover, the mounting portions 12 a and 12 a of the holding member 12 are formed, as shown in FIG. 4, at positions spaced transversely from the lower position of the steering column 3 or the arranged position of the case 19. Therefore, the works to mount the mounting portions 12 a and 12 a on the frame portions FC and FR can be done at the positions of the vehicle spaced transversely from below the steering column 3. In the airbag device S1 of the embodiment, more specifically, the arranged positions of the mounting portions 12 a and 12 a are so transversely spaced from below the steering column 3 as to retain the needed installation space. Therefore, the work to mount the airbag device S1 on the vehicle is made easier than that of the case in which the case 19 is mounted and fixed directly on the column tube 5 or the structural member of the vehicle, at the position below the steering column 3.

[0181] Of course, the holding member 12 holding the case 19 is mounted on the frame portions FC and FR by using the mounting portions 12 a and 12 a so that it can be stably held even if it houses the airbag 26 and the inflator 21.

[0182] In the first embodiment, moreover, the forward face (i.e., the vehicle side wall portion 27) of the airbag 26 which has extended and expanded is supported through the airbag cover 13 by the support face 12 c of the holding member 12. Even when the airbag 26 having extended and expanded interferes with the knees K of the driver MD, therefore, it does not move forward but can protect the knees K of the driver MD properly and stably.

[0183] In the airbag device S1 of the first embodiment, therefore, it is possible to retain the stable support of the case 19 and the airbag 26 after being extended and expanded, and to facilitate the work to mount the airbag device S1 on the vehicle.

[0184] In the embodiment, moreover, the case 19 housing the folded airbag 26 and the inflator 21 is assembled with the holding member 12 to form the airbag assembly SA1. Therefore, the airbag 26, the inflator 21, the case 19 and the holding member 12 can be transported and stored in the assembled state. As a result, it is easy to handle the individual parts such as the airbag 26 and the inflator 21 before mounted on the vehicle.

[0185] Here in the airbag device S1 thus far described, the holding member 12 is mounted and fixed on the frame portions FC and FR of the vehicle, to which the mounting portion of the vehicle for mounting and fixing the holding member 12 should not be limited. The holding member need not be directly connected and fixed to the structural member such as the frame portion of the vehicle, if it could support the holding member stably.

[0186] The mounting portion can be the lower panel 43 b of a dashboard 43, as in the airbag device S2 of a second embodiment shown in FIGS. 12 and 13. In this second embodiment, the dashboard 43 comprises an upper panel 43 a and the lower panel 43 b. Moreover, a holding member 45 is mounted and fixed on the lower panel 43 b acting as the mounting portion. In predetermined portions of the lower panel 43 b, more specifically, there are connected a plurality of bolts (e.g., eight in the shown embodiment) which protrude toward the front. Moreover, the holding member 45 is mounted and fixed on the lower panel 43 b by fastening mounting portions 45 a and 45 a, formed on the two transverse ends of the holding member 45, by means of the bolts 44. The holding member 45 is provided like the aforementioned holding member 12 in the airbag device S1, with a communication hole 45 b and a support face 45 c arranged on the periphery of the communication hole 45 b. This communication hole 45 b communicates with the opening 19 e of the case 19. The support face 45 c can support the front side face of the extending and expanding airbag 26. Moreover, the support face 45 c is made transversely wider than the airbag 26 which has extended and expanded so that it can support the face of the airbag 26 on the vehicle front side, as shown in FIG. 13. The door portion 15 is integrated with the lower panel 45 b by arranging the breakaway portion 14 having an inverted U-shape around on its peripheral edges and arranging the hinge portion 16 on its lower edge.

[0187] Here, the constructions of the airbag device S2 of the second embodiment, except for the dashboard 43 and the holding member 45, are similar to those of the aforementioned airbag device S1 of the first embodiment. Therefore, the same members will not be explained, and will be designated by the same reference numerals.

[0188] In case the airbag device S2 is given the construction thus far described, too, the mounting portions 45 a and 45 a of the holding member 45 are formed at specified positions spaced leftward and rightward from the lower position of the steering column 3 or the arranged position of the case 19, as shown in FIG. 13. Even in case the holding member 45 is mounted on the lower panel 43 b, as described above, the work to mount the mounting portions 45 a and 45 a on the lower panel 43 b are done at positions spaced transversely from the position below the steering column 3 so that it can be simplified.

[0189] Moreover, the mounting portion may be a dashboard reinforcement 48 which is a structural member of the vehicle as in an airbag device S3 of a third embodiment shown in FIGS. 14 and 15. The dashboard reinforcement 48 is formed into a pipe shape and is so arranged below the steering column 3 as to intersect the steering column 3 generally perpendicularly. Moreover, a holding member 50 is provided with a plurality of (e.g., two in the shown embodiment) mounting plates 50 a and 50 a protruding forward of the vehicle. The holding member 50 is mounted and fixed on the dashboard reinforcement 48 by fixing the vehicle front side end portion of each mounting plate 50 a on a mounting plate portion 49 fixed on the dashboard reinforcement 48, by means of a bolt 51. Moreover, the holding member 50 is integrated with the case 19 by a die-casting method, as shown in FIG. 14. Moreover, the holding member 50 is provided, like the foregoing holding members 12 and 45, with a communication hole 50 b and a support face 50 c arranged on the periphery of the communication hole 50 b. Moreover, the support face 50 c is made transversely larger than the airbag 26 having extended and expanded, as shown in FIG. 15.

[0190] Here, the constructions of the airbag device S3 of the third embodiment other than the holding member 50 are similar to those of the aforementioned airbag device S1 of the first embodiment. Therefore, the common members will be omitted from description by designating them by the common reference numerals.

[0191] In the case of the aforementioned construction of the airbag device S3, too, the mounting portions 50 a and 50 b of the holding member 50 are formed at positions spaced transversely from the specified position below the steering column 3 or the arranged position of the case 19, as shown in FIG. 15. Even in case the holding member 50 is mounted on the dashboard reinforcement 48, as described above, the work to mount the mounting portions 50 a and 50 a on the dashboard reinforcement 48 are done at the positions spaced transversely from the position below the steering column 3 so that it can be simplified.

[0192] Here in the airbag device S3 of the third embodiment, the airbag assembly is made by housing the airbag 26 and the inflator 21 in the case 19 integrated with the holding member 50 and by mounting and fixing the airbag cover 13 on the holding member 50. Moreover, this airbag assembly is mounted on the vehicle by using the mounting portions 50 a and 50 a.

[0193] The first to third embodiments have been described by exemplifying the airbag devices S1 to S3 arranged on the vehicle front side of the driver MD so as to protect the knees of the driver MD. In order to protect the knees of a passenger MP seated on the passenger's seat, however, the airbag device S1 may be arranged in front of the passenger MP seated on the rider's seat, as shown in FIG. 16. Here in the shown example, the mounting portions 12 a and 12 a formed at the left and right ends of the holding member 12 for holding the case are individually connected and fixed to the left and right frame portions FL and FC as the mounting portions of the vehicle, by means of the bolts 41. The frame portion FL is a front body pillar in the body of the vehicle, and the frame portion FC is a center brace in the body of the vehicle.

[0194] In the airbag devices S1 to S3 of the first to third embodiments, moreover, the mounting portion of the vehicle for mounting and fixing the holding members 12, 45 and 50 need not be limited to the aforementioned ones. The mounting portion may be the column tube 5 or the like. In the holding members 12, 45 and 50, moreover, the mounting portions 12 a, 45 a and 50 a are formed at specified positions spaced transversely away from the case 19. However, the positions for forming the mounting portions should not be limited thereto but may be located for example to be vertically spaced away from the case 19.

[0195] Here will be described a knee protecting airbag device S4 capable of achieving the second object of the invention.

[0196] The knee protecting airbag device S4 of a fourth embodiment is arranged below the steering column 3 or on the vehicle front side of the driver MD, as shown in FIGS. 17 to 20, so as to protect the knees K of the driver MD as the passenger M.

[0197] Here, the constructions of the vehicle mounted the airbag device S4 of the fourth embodiment other than a dashboard 112 are similar to those of the aforementioned airbag device S1 of the first embodiment. Therefore, the common members will be omitted on their description by designating them by the common reference numerals.

[0198] The knee protecting airbag device S4 comprises a folded airbag 26A, an inflator 141, an airbag cover 130, and a knee panel 116 as the holding member. In the airbag device S4 of the embodiment, moreover, the airbag 26A, the inflator 141 and the airbag cover 130 are assembled with the knee panel 116 to make an airbag assembly SA2 (see FIGS. 25 and 26). Moreover, the airbag assembly SA2 thus integrated by assembling those individual parts is mounted on the vehicle, and the airbag device S4 is mounted on the vehicle.

[0199] The knee panel 116 is made of a sheet metal and is provided with a body portion 117 having a flat shape, and a housing portion 123, as shown in FIGS. 18 to 22. The housing portion 123 houses the folded airbag 26A and the inflator 141.

[0200] The housing portion 123 is formed into a bottomed box shape having an opening 123 a sloping downward toward the rear. In the case of the embodiment, the housing portion 123 is formed into a generally rectangular box shape. The housing portion 123 has a bottom wall portion 126 of a generally rectangular shape and a peripheral wall portion 124 of a generally rectangular tubular shape. In the peripheral wall portion 124 surrounding the opening 123 a, moreover, mounting holes 127 and 128 of larger and smaller diameters for mounting the inflator 141 are individually formed in wall portions 124 a and 124 b which are positioned in the transverse direction. The mounting hole 127 is constructed to insert thereinto the later-described cylindrical body portion 141 a of the inflator 141. Moreover, the mounting hole 127 can support the outer circumference of the body portion 141 a on its inner circumference. The mounting hole 128 is too small to insert the body portion 141 a of the inflator 141 but to allow a screw portion 141 c of the inflator 141 to pass. The inflator 141 is mounted in the housing portion 123 in the following manner. First of all, the inflator 141 is so inserted into the mounting hole 127 from the outside of the housing portion 123 as to protrude the screw portion 141 c from the mounting hole 128. After this, a nut 142 is screwed on the screw portion 141 c.

[0201] On the outer circumference of the peripheral wall portion 124, moreover, there are fixed a plurality of hooks 125 which have a generally J-shaped section. Each hooks 125 has a retaining hook portion 125 a at the top end. The individual retaining hook portion 125 a is inverted to the bottom wall portion 126 side. In the case of the embodiment, moreover, there are arranged nine hooks 125. Specifically, four hooks 125 are arranged at positions (on the lower portion of the peripheral wall portion 124) along the later-described hinge portion 137 in the airbag cover 130. Moreover, three hooks 125 are arranged at positions (on the upper face side of the peripheral wall portion 124) along the leading edge 139 a of the later-described door portion 139 of the airbag cover 130. As shown in FIG. 19, moreover, one hook 125 is arranged, respectively, on the portions arranged in the transverse direction of the peripheral wall portion 124.

[0202] The body portion 117 is formed into a generally rectangular shape extending from the periphery of the opening 123 a of the housing portion 123. The body portion 117 is positioned on the front sides of the left and right knees K (KL and KR) of the seated driver MD. At the four corners of the periphery in the body portion 117, individually, there are arranged mounting members 121 for connecting the body portion 117 to the body 101 of the vehicle. Here in the vicinity of the upper edge side of the opening 123 a in the body portion 117, there is formed a recess 117 a for the protruding lower face 8 a of the column cover 8. The upper edge of the opening 123 a in the body portion 117 is so curved as to protrude toward the rear in a manner to match the curved state of the column cover lower face 8 a. Between the periphery of the opening 123 a and the outer periphery of the body portion 117, there are formed ribs 118 a for enhancing the rigidity of the body portion 117. The rear-facing surface of each rib 118 a constructs a support portion 118 for supporting the later-described general portion 131 of the airbag cover 130.

[0203] Along the periphery of the housing portion opening 123 a of the body portion 117, moreover, there are formed a plurality of through holes 119. Each through hole is opened in a generally rectangular shape. These through holes 119 can pass mounting members 133 to be retained on the individual hooks 125 in the airbag cover 130. Moreover, the individual through holes 119 are arranged on the body portion 117 corresponding to the individual retaining hook portions 125 a along the peripheral wall portion 124.

[0204] On the left and right sides apart from the housing portion 123 in the body portion 117, moreover, there are formed a plurality of mounting holes 120 which is arranged through the body portion 117. These mounting holes 120 are portions for mounting the airbag cover 130 on the knee panel 116 by using the thermal caulking method. This airbag cover 130 is mounted on the knee panel 116 in the following manner. First of all, the later-described mounting leg portions 132 of the airbag cover 130 are inserted into the individual mounting holes 120. After this, the leading ends 132 a of the individual mounting leg portions 132 are melted and radially enlarged so that they are prevented after solidifying from coming out of the mounting holes 120. In short, the airbag cover 130 is mounted on the knee panel 116 by using the mounting leg portions 132 and the hooks 125 together.

[0205] In the individual joining members 121 of the knee panel 116, moreover, there are formed joint holes 121 a for mounting the knee panel 116 on the side of the body 101 by means of bolts 129 (see FIG. 20). For mounting the individual joining members 121, moreover, there are arranged brackets 103 and 104 at the body 101 side. These brackets 103 and 104 serve as kinetic energy absorbing members for absorbing the kinetic energy of the knees K of the driver MD. When the airbag 26A completes the extension and expansion and is pushed by the knees K of the driver MD, the airbag 26A cannot absorb all the kinetic energy of the knees K, in case that the passenger side wall portion 28 of the airbag 26A contacts the vehicle side wall portion 27, pushed by the knees K. At this time, the brackets 103 and 104 plastically deform and absorb the forward energy from the knees K. Moreover, the brackets 103 and 104 elastically deform even if the knees K of the passenger MD interfere with the knee panel 116 while the airbag 26A is in the unexpanded state. The brackets 103 and 103 are connected to the dashboard reinforcement 48 on the side of the body 101. The brackets 104 and 104 are connected to the not-shown center brace or front body pillar of the body 101.

[0206] Here, the embodiment has been described where the knee panel 116 connected to the body portion 117 and the housing portion 123 is pressed into one unit. However, the knee panel 116 may be suitably formed by welding a sheet metal.

[0207] The airbag cover 130 is made of a thermoplastic elastomer such as polyolefin. The airbag cover 130 is given a larger external shape than that of the knee panel 116, as shown in FIGS. 18 to 22, so that it may be able to cover the rear-facing side of the knee panel 116.

[0208] Here, the airbag cover 130 is arranged on the side of the lower panel 112 b on the periphery of the column cover 8 in the dashboard 112 which is composed of an upper panel 112 a and a lower panel 112 b. The airbag cover 130 covers the lower side periphery of the column cover 8 protruding from the dashboard 112. For this purpose, the airbag cover 130 is provided near the center, as viewed from the vehicle rear, with a recessed portion 130 d which allows to protrude the column cover 8 to the rear side. Below the recessed portion 130 d in the airbag cover 130, there is arranged a raised portion 130 c which is so curved to the rear of the vehicle on its upper edge side as to match the curved face on the side of the column cover lower face 8 a. On the two left and right sides of the raised portion 130 c in the airbag cover 130, moreover, there are arranged flat portions 130 a and 130 b which extend to cover the two left and right sides of the body portion 117 of the knee panel 116.

[0209] Moreover, the airbag cover 130 comprises the door portion 139 for covering the opening 123 a of the housing portion 123, and the general portion 131 for covering the vehicle rear side of the body portion 117.

[0210] The door portion 139 is arranged below the raised portion 130 c. The door portion 139 is formed into a generally rectangular plate shape for covering the opening 123 a slightly more than necessary. At the inverted U-shaped portion of the outer periphery of the door portion 139, there is formed a breakaway portion 135 which is so thinned and connected to the general portion 131 that the door portion 139 may be opened downward. The breakaway portion 135 is so formed to have continuous or interrupted grooves on the vehicle front side face that it could be easily broken when the door portion 139 is pushed by the expanding airbag 26A.

[0211] On the lower edge side of the door portion 139, moreover, there is formed the hinge portion 137, which provides a pivot for the door portion 139 when the breakaway portion 135 is broken to allow the door portion 139 to open. The hinge portion 137 is an integral hinge having such a thickness smaller than that of the general portion 131 and the door portion 139 as is within the unbreakable range.

[0212] In the vicinity of the entire periphery of the housing portion opening 123 a in the general portion 131, moreover, the mounting members 133 protrude forward. Each of these mounting members 133 extends through each through hole 119 in the body portion 117 of the knee panel 116. Each mounting members 133 is formed into a generally rectangular plate shape. In each mounting member 133, there is formed a retaining hole 133 a which is opened in a rectangular shape. This retaining hole 133 a is held by the retaining hook portion 125 a of the hook 125.

[0213] At the predetermined positions of the general portion 131, on the other hand, there are formed the mounting leg portions 132. Each mounting leg portion 132 is thermally caulked and retained in each mounting hole 120 in the body portion 117 of the knee panel 116. As shown in FIGS. 22 and 25, each mounting leg portion 132 is formed to have such a rod shape before thermally caulked as to be insertable into the mounting hole 120. As shown in FIGS. 19 and 26, moreover, each mounting leg portion 132 is provided at its leading end with the head portion 132 a which is crushed after being thermally caulked. On the root side of each mounting leg portion 132, there is formed a root portion 132 b of a column or cross shape, which abuts against the body portion 117 when the head portion 132 a is thermally caulked and fixed in the mounting hole 120.

[0214] The inflator 141 is, as shown in FIGS. 17 to 19, of the cylinder type capable of discharging the inflating gas G when fed with the electric signal. The inflator 141 has the cylindrical body portion 141 a provided with gas discharge ports 141 b. In the inflator 141, moreover, the screw threaded portion 141 c protrudes from one end of the body portion 141 a. This inflator 141 is held in the following manner in the housing portion 123, as has been described hereinbefore. Specifically, the inflator 141 is inserted into the housing portion 123 in the knee panel 116 from the mounting hole 127, and the nut 142 is fastened on the screw portion 141 c protruding from the mounting hole 128. Then, the screw portion 141 c side face of the body portion 141 a is pressed to the periphery of the mounting hole 128 of the housing portion 123. At this time, the face of the body portion 141 a separate from the screw portion 141 c is supported on the inner circumference of the mounting hole 127. The inflator 141 extends, when housed in the housing portion 123, through the later-described mounting holes 27 e and 27 f of the airbag 26A.

[0215] Like the aforementioned inflator in the airbag device S1, moreover, the inflator 141 is activated when fed with the electric signal from the control device for activating the not-shown airbag device mounted on the steering wheel 1, simultaneously with the airbag device for the steering wheel. On the end of the body portion 141 a that protrudes out of the housing portion 123, there is arranged a connector 143 which is connected with a lead wire 144 connected with the airbag activating circuit.

[0216] The airbag 26A used has a construction similar to the airbag 26 in the airbag device S1 of the first embodiment. Therefore, the description will be omitted by designating the common reference numerals. In the lower side of the vehicle side wall portion 27 in the airbag 26A, there are formed the two mounting holes 27 e and 27 f. The mounting hole 27 e has such an internal diameter substantially equal to the external diameter of the body portion 141 a as can insert the body portion 141 a of the inflator 141 thereinto. The mounting hole 27 f has such an internal diameter smaller than the external diameter of the body portion 141 a but which can pass the screw portion 141 c thereinto. Moreover, the airbag 26A is mounted on the knee panel 116 in the following manner. First of all, the inflator body portion 141 a is inserted into the mounting hole 27 e of the airbag 26A, and the screw portion 141 c is inserted into the mounting hole 27 f. At this time, the inner circumferences of the mounting holes 27 e and 27 f are supported by the body portion 141 a and the screw portion 141 c of the inflator 141. Moreover, the airbag 26A is mounted on the knee panel 116 by using the inflator 141 which is housed in the housing portion 123.

[0217] Here will be described how to mount the airbag device S4 on the vehicle. Like the aforementioned airbag 26 in the airbag device S1 of the first embodiment, the airbag 26A is folded at first. The airbag 26A is wrapped, after being folded up, with the not-shown breakable wrapping film so that it may not become loose. After this, the airbag 26A is so housed in the housing portion 123 that the mounting holes 127 and 27 e and the mounting holes 128 and 27 f may match each other. Here, the wrapping film is broken in advance at the portions of the mounting holes 27 e and 27 f.

[0218] After this, the side of the screw portion 141 c of the inflator 141 is inserted from the mounting holes 127 and 27 e into the airbag 26A housed in the housing portion 123. Moreover, the nut 142 is fastened on the screw portion 141 c protruding from the mounting holes 27 f and 128, and the end face of the body portion 141 a on the side of the screw portion 141 c is pushed through the periphery of the mounting hole 27 e of the airbag 26A to contact with the inner circumference of the housing portion 123. Then, the inflator 141 and the airbag 26A can be mounted in the housing portion 123.

[0219] Then, the airbag cover 130 is mounted on the knee panel 116. For this, as shown in FIGS. 25 and 26, the mounting members 133 are inserted at first into the corresponding through holes 119 from the vehicle rear side of the knee panel 116. Simultaneously with this, the rounded rod-shaped head portions 132 a of the mounting leg portions 132 are inserted into the corresponding mounting holes 120.

[0220] At this time, the individual mounting members 133 are elastically deformed to separate from the housing portion 123, as indicated by double-dotted lines in FIGS. 25 and 26, through interfering with curved guide faces 125 b on the rear side of the retaining hook portions 125 a of the hooks 125. If the retaining holes 133 a are arranged at the positions of the retaining hook portion 125 a, the mounting members 133 are restored. Then, the retaining hook portions 125 a are inserted into the retaining holes 133 a. In other words, the periphery of the retaining holes 133 a is automatically held by the object-catching tips 125 a merely by inserting the mounting members 133 into the through holes 119.

[0221] Moreover, the head portions 132 a of the mounting leg portions 132 protruding from the individual mounting holes 120 are heated and thermally caulked to larger diameters with the root portions 132 b of the mounting leg portions 132 abutting against the periphery of the mounting holes 120, so that they are retained on the periphery of the mounting holes 120 on the front side face of the body portion 117 of the knee panel 116. As a result, the airbag cover 130 can be mounted on the knee panel 116 to form the airbag assembly SA2.

[0222] When this airbag assembly SA2 is connected by fastening the individual joining members 121 of the body portion 117 on the brackets 103 and 104 on the body 101 side by means of the bolts 129, the knee protecting airbag device S4 can then be mounted on the vehicle.

[0223] After the airbag device S4 was mounted on the vehicle, the lead wire 144 is connected with the airbag activating circuit, and the upper panel 112 a and the lower panel 112 b of the dashboard 112 and an under cover 114 (see FIGS. 17 and 18) is mounted on the vehicle.

[0224] If the predetermined electric signal is inputted to the inflator 141 after the airbag device S4 was mounted on the vehicle, the inflating gas G is discharged from the gas discharge ports 141 b to inflate the airbag 26A. Then, the airbag 26A breaks the not-shown wrapping film and pushes the door portion 139 of the airbag cover 130 thereby to break the breakaway portion 135, so that the door portion 139 is opened downward on the hinge portion 137. As a result, the airbag 26A protrudes backward of the vehicle from the opening 123 a of the housing portion 123 through an opening 140 of the airbag cover 130. Moreover, the airbag 26A extends and expands largely upward (see FIGS. 27 and 28) along the column cover lower face 8 a while being transversely and vertically unfolded.

[0225] At the airbag cover 130 in the airbag device S4 of the embodiment, moreover, the mounting members 133 arranged at the portions near the periphery of the opening 123 a in the general portion 131 are mounted on the housing portion 123 through the through holes 119 of the knee panel 116. During the extending and expanding of the airbag 26A, therefore, the breakaway portion 135 and the hinge portion 137 of the general portion 131 at the portions near the periphery of the opening 123 a hardly move at all relative to the housing portion 123. As a result, the pushing force of the airbag 26A acts properly to break the breakaway portion 135 smoothly. Moreover, the hinge portion 137 for providing the pivot at the opening time hardly moves at all relative to the housing portion 123 so that it can stabilize the opening action of the door portion 139. Therefore, the door portion 139 can smoothly open when pushed by the airbag 26A, even if the airbag cover 130 is made of a synthetic resin such as a thermally plastic elastomer.

[0226] In the fourth airbag device S4, therefore, the door portion 139 can be smoothly opened by the push of the airbag 26A, even when the airbag cover 130 having the integrated door portion 139 is mounted on the knee panel 116 (as the holding member) arranged in front of the knees K of the driver MD.

[0227] In order to retain the smooth breakage of the breakaway portion 135 and the smooth opening action of the door portion 139, the mounting members 133 to be mounted on the housing portion 123 through the body portion 117 of the knee panel 116 may be arranged on the periphery of the opening 123 a at the vicinity of the breakaway portion 135 on the leading edge 139 a side of the opening door portion 139 opposite from the hinge portion 137 and the vicinity of the hinge portion 137.

[0228] However, the smooth breakage of the breakaway portion 135 and the stable opening action of the door portion 139 can be better retained, if the mounting members 133 are arranged on the entire periphery of the generally rectangular opening 123 a in the housing portion 123 as in the embodiment.

[0229] In the case of the embodiment, moreover, one door portion 139 is opened to allow the airbag 26A to protrude from the opening 140. However, the shape of the door portion should not be limited thereto, but the opening 123 a of the housing portion 123 may be covered with two double-open door portions such as double-hinged doors. In this case, the breakaway portion is arranged in the shape of letter “H” or Japanese letter “I”, as viewed from the vehicle rear side. In such case, the hinge portions are arranged between the ends of the vertical portions of the letter “H” positioned at the left and right sides. If the breakaway portion is formed in the shape of Japanese letter “I”, moreover, the hinge portions are arranged between the ends of the horizontal portions of the letter “I” positioned at upper and lower sides. In these cases, moreover, it is desired that the mounting members are arranged at least on the periphery of the housing opening in the vicinity of the hinge portions.

[0230] Moreover, if the mounting members 133 are arranged only one side of the periphery of the opening 123 a of a generally rectangular shape (e.g., on the side of the wall portions 124 a and 124 b), one suitably enlarged mounting member 133 may be so arranged that it can retain the mounting strength. Alternatively, a plurality of mounting members 133 may be arranged (on the upper side or lower side of the periphery of the opening 123 a).

[0231] Still moreover, the individual mounting members 133 of the airbag cover 130 of the embodiment are merely inserted into the through holes 119 in the periphery of the opening 123 a of the knee panel 116 so that the body portion 117 of the knee panel 116 is not reduced in its frontal area. Thus, in an unexpanded state of the airbag 26A, even if the two knees K (KL and KR) of the driver MD interfere with the body portion 117, the knee panel 116 can catch the two left and right knees KL and KR over a wide area. In this mode, the body portion 117 of the knee panel 116 can support the front side of the airbag 26A which has completed its expansion through the general portion 131 of the airbag cover 130, so that the airbag 26A which has completed its extension and expansion is stably supported by the body portion 117 of the knee panel 116.

[0232] In the knee protecting airbag device S4 of the fourth embodiment, moreover, the airbag 26A, the inflator 141, the airbag cover 130 and the knee panel 116 can be integrated in advance into the airbag assembly SA2. If this airbag assembly SA2 is formed in advance, therefore, the airbag 26A and so on can be transported and stored in the assembly state. As a result, the individual members are easily handled till they are mounted on the vehicle.

[0233] In the airbag device S4 of the fourth embodiment, still moreover, the individual hooks 125 of the housing portion 123 are inserted into the retaining holes 133 a of the individual mounting members 133 of the airbag cover 130 to retain the mounting members 133 with the retaining hook portions 125 a of the individual hooks 125, so that the mounting members 133 can be completely mounted on the housing portion 123. It is, therefore, possible to reduce the number of steps of and the cost for mounting the airbag cover 130 on the knee panel 116. Especially in the embodiment, the individual mounting members 133 are automatically loosened merely by inserting them into the through holes 119, and the periphery of the retaining holes 133 a are retained on the retaining hook portions 125 a so that the number of mounting steps can be further reduced. If this is not used, the individual mounting members 133 may be mounted on the housing portion 123 by using bolts, nuts or rivets without providing the hooks 125.

[0234] In the airbag device S4 of the fourth embodiment, still moreover, the brackets 103 and 104 acting as the energy absorbing members are arranged on the body 101 side for connecting the joining portions 121 of the knee panel 116. When the airbag 26A is completely depressed so that the kinetic energy of the knees K cannot be further absorbed by the airbag 26A, therefore, the brackets 103 and 104 are plastically deformed to absorb the forward kinetic energy of the knees K. Moreover, the brackets 103 and 104 are plastically deformed in the unexpanded state of the airbag 26A even if the knees K of the driver MD interfere with the knee panel 116. Therefore, the knees K of the driver MD can be properly protected by lessening the impact.

[0235] Here, the fourth embodiment has been described by exemplifying the airbag device S4 which is in front of the seated driver MD so as to protect the knees K of the driver MD. In order to protect the knees of the passenger MP seated on the passenger's seat, however, the airbag device S4 may be in front of the passenger MP seated on the passenger's seat, as shown in FIG. 29.

[0236] Here will be described a knee protecting airbag device S5 capable of achieving the third object of the present invention.

[0237] As shown in FIG. 30, the constructions of this airbag device S5 other than the knee panel 216 as the holding member are similar to those of the aforementioned airbag device S4 of the fourth embodiment. Therefore, the same members will not be described and will referred to by the same reference numerals.

[0238] The knee protecting airbag device S5 comprises the folded knee protecting airbag 26A, the inflator 141, a case 223 for housing the airbag 26A and the inflator 141, the airbag cover 130 for covering the vehicle rear side in the opening 223 a of the case 223, and a knee panel 216. The case 223 is provided with the opening 223 a which allows the airbag 26A when extending and expanding to protrude toward the rear. In the embodiment, moreover, an airbag assembly SA3 as the airbag module comprises the airbag 26A, the inflator 141 and the case 223 (or the knee panel 216) and the airbag cover 130. In the case of the embodiment, the case 223 is formed integrally with the knee panel 216 by pressing one metal sheet. Of course, the case 223 and the knee panel 216 may be formed separately of each other and assembled by using the bolts, nuts and rivets and the welding method.

[0239] The case 223 is formed into a bottomed box shape having an opening 223 a on the vehicle rear side, as shown in FIGS. 31, 32, 34 and 35. In the case of the embodiment, the case 223 is formed into a generally parallelepiped box shape including a bottom wall portion 226 of a generally rectangular shape and a peripheral wall portion 224 of a generally rectangular tubular shape. In the peripheral wall portion 224 of the case 223, mounting holes 227 and 228, one made large and one made small for mounting the inflator 141, are arranged in wall portions 224 a and 224 b positioned in the transverse direction. The mounting hole 227 is so formed to insert thereinto the body portion 141 a of the inflator 141 that can support the outer circumference of the body portion 141 a on its inner circumference. The mounting hole 228 is given an internal diameter to small for the body portion 141 a of the inflator 141 but which can allow the screw portion 141 c of the inflator 141 to protrude through. The inflator 141 is mounted in the case 223 in the same way that it is mounted in the housing portion 123 in the airbag device S4 of the fourth embodiment.

[0240] The hooks 125 are fixed on the outer circumference of the peripheral wall portion 224 as in the housing portion 123 in the airbag device S4 of the fourth embodiment.

[0241] The knee panel 216 as the holding member comprises, as shown in FIGS. 31 to 35, a plate-shaped portion 217 and four mounting portions 222. The plate-shaped portion 217 extends vertically and transversely from the periphery of the opening 223 a of the case 223. Moreover, the plate-shaped portion 217 is formed into such a generally rectangular shape as to cover widely in front of the two left and right knees K (KL and KR) of the seated driver MD. The plate-shaped portion 217 is arranged on the vehicle front side in the region of the lower expansion portion 30 of the airbag 26A which has completed its expansion. The individual mounting portions 222 are arranged at the four corners of the periphery of the plate-shaped portion 217.

[0242] From the periphery of the opening 223 a to the outer periphery of the plate-shaped portion, moreover, there are formed ribs 218 for enhancing the bending rigidity of the plate-shaped portion 217. In the case of the embodiment, those ribs 218 are formed into a U-shaped section and are formed integrally with the plate-shaped portion 217 by pressing it. Moreover, the ribs 218 support the general portion 131 of the airbag cover 130 on the rear-facing side.

[0243] Moreover, the plate-shaped portion 217 is bent at its outer periphery forward and is provided with a flange portion 221 for enhancing the bending rigidity thereof.

[0244] These ribs 218 and flange portion 221 are so constructed by setting the number, shapes and arranged positions as to shorten the deformation stroke of the plate-shaped portion 217 at the time the plate bends forward to absorb the kinetic energy of the knees K smoothly. In the case of the embodiment, moreover, the bending deformation load of the plate-shaped portion 217 is so set that the plate-shaped portion 217 may start a bending plastic deformation when the airbag 26A which has extended and expanded is pushed flat at one portion by the knees K against its internal pressure. At this time, the vehicle side wall portion 27 of the airbag 26A comes into abutment against the general portion 131 of the airbag cover 130, and the passenger side wall portion 28 comes into contact with the column cover side wall portion 27.

[0245] In the periphery of the opening 223 in the plate-shaped portion 217, on the other hand, there are formed a plurality of through holes 219 which extend through the periphery. The individual mounting members 133 of the airbag cover 130 are so inserted into those through holes 219 as to retain the mounting members 133 on the individual hooks 125.

[0246] In the two left and right sides apart from the case 223 in the plate-shaped portion 217, moreover, there are formed a plurality of mounting holes 220 which extend therethrough. These mounting holes 220 are portions at which the airbag cover 130 is mounted on the knee panel 216 by thermally caulking it. This airbag cover 130 is mounted on the knee panel 216 like the airbag cover 130 mounted on the knee panel 116 in the aforementioned airbag device S4.

[0247] Each of the mounting portions 222 of the knee panel 216 is provided with a joint hole 222 a for mounting it on the side of the body 101 by means of a bolt 229 (FIG. 33). On the side of the body 101 for mounting the mounting portions 222, there are arranged brackets 203 (FIG. 32). These brackets 203 are connected to rigid portions such as the not-shown dashboard reinforcement, center brace or front body pillar on the side of the body 101.

[0248] This airbag device S5 can be mounted on the vehicle like the airbag device S4 of the fourth embodiment. Specifically, the airbag 26A and the inflator 141 are mounted in the case 223, and the airbag cover 130 is mounted on the knee panel 216 as in the aforementioned airbag device S4. As a result, the airbag assembly SA3 can be formed as the airbag module.

[0249] When the individual joining members 222 of the plate-shaped portion 217 in the knee panel 216 are connected to the brackets 203 on the side of the body 101 by means of the bolts 229, moreover, the knee protecting airbag device S5 can be mounted on the vehicle.

[0250] In the airbag device S5 of the fifth embodiment, when the airbag 26A is extended and expanded, the knees K are cushioned by the expanded lower expansion portion 30. At this time, if the lower expansion portion 30 of the airbag 26A is flattened at one position so that the kinetic energy E of the knees K cannot be completely absorbed by the lower expansion portion 30, the plate-shaped portion 217 of the knee panel 216 as the holding member receives the pushing force of the knees K through the airbag 26A through the general portion 131 of the airbag cover 130. As a result, the plate-shaped portion 217 of the knee panel 216 is plastically bent and deformed to absorb the excessive kinetic energy of the knees K.

[0251] Moreover, the plate-shaped portion 217 of the knee panel 216 extends from the periphery of the opening 223 a of the case 223 so that it may be arranged toward the vehicle front in the area of the lower expansion portion 30 of the airbag which has completed its expansion. Therefore, the kinetic energy of the knees K can be properly absorbed by the plate-shaped portion 217 through the lower expansion portion 30 of the airbag 26A which has completed its expansion.

[0252] Of course, the plate-shaped portion 217 of the knee panel 216 is so extended from the periphery of the opening 223 a of the case 223 that it is arranged toward the vehicle front in the area of the lower expansion portion 30 upon completion of the expansion. In other words, the plate-shaped portion 217 of the knee panel 216 is arranged with a large flat area vertically and transversely. Even with a small deformation stroke d at the time of absorbing the kinetic energy E, therefore, the kinetic energy of the knees K can be sufficiently absorbed by the plate-shaped portion 217 of the knee panel 216.

[0253] In the knee panel 216 serving as the holding member, moreover, the portions to be fixed on the vehicle body are the mounting portions 222 arranged near the periphery of the plate-shaped portion 217, and the mounting portions 222 do not obstruct the deformation of the plate-shaped portion 217.

[0254] Moreover, the plate-shaped portion 217 of the knee panel 216 does not extend longitudinally like the mounting brackets of the prior art. Specifically, the plate-shaped portion 217 of the knee panel 216 is so extended from the periphery of the opening 223 a of the case 223 and arranged in the flat shape vertically and transversely that it may be arranged toward the vehicle front in the area of the airbag lower expansion portion 30 upon completion of the expansion. Even if there is less space in front side of the airbag assembly SA3 as the airbag module, therefore, it is easy to install the airbag assembly SA3.

[0255] In the knee protecting airbag device S5 of the fifth embodiment, therefore, the kinetic energy E of the knees K can be absorbed, even when it cannot be received by the airbag 26A, and the degree of mounting freedom on the vehicle can be improved.

[0256] In the airbag device S5 of the fifth embodiment, moreover, the ribs 218 capable of adjusting the absorption quantity of the kinetic energy by the knees K are arranged on the plate-shaped portion 217 of the knee panel 216, and the flange portion 221 capable of adjusting the absorption quantity of the kinetic energy of the knees K is also arranged on the periphery of the plate-shaped portion 217. By setting the number, shapes and arranged positions of those ribs 218 and flange portion 221, therefore, the absorption quantity of the kinetic energy can be easily adjusted to match the deformation stroke or the like of the plate-shaped portion 217.

[0257] Here in the embodiment, the mounting portions 222 of the knee panel 216 are formed to extend forward from the vicinity of the periphery of the plate-shaped portion 217. However, the mounting portions 222 arranged near the periphery of the plate-shaped portion 217 in the knee panel 216 need not be extended much forward from the periphery of the plate-shaped portion 217. If the airbag assembly SA3 can be mounted and fixed on a predetermined portion of the vehicle body, it can be arranged to extend transversely from the periphery of the plate-shaped portion 217, as indicated by double-dotted lines in FIG. 32, so that it can be located at a rigid portion such as the not-shown dashboard reinforcement, center brace or front body pillar on the side of the body 101. In this case, the airbag device S5 can be made shorter and more compact in the longitudinal directions of the vehicle to improve the degree of freedom for mounting on the vehicle.

[0258] In the embodiment, moreover, the plate-shaped portion 217 of the knee panel 216 is plastically bent and deformed at the time of absorbing the kinetic energy of the knees K. However, the mounting portion 222 may be so constructed to buckle and be deformed that the knee panel 216 can absorb more energy. Moreover, the plate-shaped portion 217 may be modified to absorb the kinetic energy of the knees K not only by the plastic deformation but instead by brittle fracture, employing a brittle material.

[0259] Moreover, the fifth embodiment has been described by exemplifying the airbag device S5 which is arranged in front of the driver MD so as to protect the knees K of the driver MD. In order to protect the two knees of the passenger of the passenger seat, however, the airbag device S5 may be arranged at a position in front of the passenger seated on the passenger's seat.

[0260] Here will be described knee protecting airbag devices S6 to S8 capable achieving the fourth object of the invention.

[0261] Here, the constructions of the vehicle for mounting the knee protecting airbag device S6 of the sixth embodiment are similar to those of the aforementioned airbag device S1 of the first embodiment except for dashboard 312. Therefore, the same members will not be described and will given the same reference numerals.

[0262] The knee protecting airbag device S6 of the sixth embodiment is arranged below the steering column 3 on the vehicle front side of the driver MD, as shown in FIGS. 38 to 41, so that it may be able to protect the knees K of the driver MD or the passenger M.

[0263] The knee protecting airbag device S6 comprises a folded airbag 26B, an inflator 337, a case 315 for housing the folded airbag 26B and the inflator 337, and an airbag cover 322. The case 315 is opened toward the rear of the vehicle.

[0264] The case 315 is made of a sheet metal. The case 315 includes a peripheral wall portion 316 of a generally rectangular tubular shape and a bottom wall portion 318 for closing the vehicle front side of the peripheral wall portion 316. On the outer peripheral faces of wall portions 316 a and 316 b, which are vertically opposite to each other, moreover, there are fixed a plurality of hooks 317 having roughly C-shape. Each of these hooks 317 has a retaining hook portion 317 a at the top end. The retaining hook portion 317 a is inverted to the bottom wall portion 318 side. In the embodiment, four hooks 317 are arranged on the wall portion 316 a, and three hooks 317 are arranged on the wall portion 316 b. In the wall portion 316 c of the peripheral wall portion 316, moreover, there is formed an insert hole 316 e which can hold the end portion of the later-described body 338 of the inflator 337 (see FIG. 40). In the bottom wall portion 318, there are formed insert holes 318 a for passing the later-described bolts 339 f of the inflator 337. This case 315 is connected and fixed to the not-shown dashboard reinforcement arranged near the steering column 3, by using not-shown brackets.

[0265] Near the later-described door portion 334 of the airbag cover 322 in the case 315, moreover, there is arranged a guide wall portion 319 serving as extension promoting means. The guide wall portion 319 is constructed to extend from the rear edge of the wall portion 316 b and to cover the lower side of the opening 315 a. This guide wall portion 319 is arranged, as shown in FIG. 39, along the door portion 334 of the airbag cover 322. Specifically, the guide wall portion 319 is arranged its upper side on the rear side and is inclined to intersect obliquely the plane perpendicular to the longitudinal direction of the vehicle.

[0266] The airbag cover 322 is made of a thermoplastic elastomer such as polyolefin. Moreover, the airbag cover 322 covers the vehicle rear side of the case 315.

[0267] Moreover, the airbag cover 322 is arranged on the periphery of the column cover 8 on a lower panel 312 b side of the dashboard 312. The airbag cover 322 covers the lower side periphery of the column cover 8 protruding from the dashboard 312. Therefore, as viewed from the vehicle rear side, the airbag cover 322 is so recessed downward at the vicinity of the upper edge center as to be protruded with the column cover 8 backward. Moreover, the airbag cover 322 is constructed by raising the upper edge side below the recess to curve backward in a manner to match the curved face of the column cover lower portion 8 a. Furthermore, the airbag cover 322 is so integrally formed by an injection molding method or the like as to include the door portion 334 for covering the opening 315 a of the case 315 and a general portion 324 arranged around the door portion 334.

[0268] The door portion 334 is formed into a generally rectangular plate shape slightly larger than the opening 315 a for covering the opening. The door portion 334 arranges a hinge portion 332 at its lower end for providing the pivot when it opens. The door portion 334 has a thinned breakaway portion 331 arranged at the inverted U-shape portion of the outer periphery excepting the hinge portion 332. Moreover, the door portion 334 is arranged at such an inclination as to intersect the vertical direction perpendicular to the longitudinal direction of the vehicle. In the door portion 334, more specifically, the side of an upper end 334 a is arranged on the vehicle rear side, and the hinge portion 332 is arranged on the vehicle front side. The hinge portion 332 is made of an integral hinge and is made thinner than the general portion 324 and the door portion 334 but still within the unbreakable range. The breakaway portion 331 is so formed to have continuous or interrupted grooves in the front face so that it may be easily broken when the door portion 334 is pushed by the expanding airbag.

[0269] At portions of the general portion 324 near the periphery of the door portion 334, there are arranged four side wall portions 327, 328, 329 and 330. These individual side wall portions 327, 328, 329 and 330 protrude forward on the outer peripheral side of the case 315. Moreover, the upper side wall portion 327 arranged on the upper side of the case peripheral wall portion 316 and the lower side wall portion 328 arranged on the lower side of the case peripheral wall portion 316 are mounting wall portions for mounting the airbag cover 322 on the case 315. The upper and lower side wall portions 327 and 328 are provided with retaining holes 327 a and 328 a, respectively, for retaining the retaining hook portions 317 a of the hooks 317 arranged on the peripheral wall portion 316.

[0270] The upper side wall portion 327 serves as extension promoting means together with the hooks 317 of the case 315. The upper side wall portion 327 is arranged transversely near above the upper end breakaway portion 331 a arranged at the upper end of the door portion 334. Also, the upper side wall portion 327 is arranged along the upper end breakaway portion 331 a. The upper side wall portion 327 is retained on the peripheral wall portion 316 of the case 315 by using the hooks 317. In the embodiment, more specifically, the portion near the upper end breakaway portion 331 a on the door upper end 334 a side is firmly connected to the case 315 by the upper side wall portion 327 and the hooks 317. When the airbag 26B protrudes, therefore, the area of the upper end breakaway portion 331 a is not moved relatively to the case 315 even when pushed by the airbag 26B, so that the breakaway portion 331 a can be smoothly broken by the airbag 26B.

[0271] At predetermined positions in the general portion 324, on the other hand, there are formed mounting leg portions 325 which extend forward of the vehicle. These mounting leg portions 325 are arranged to mount and fix the airbag cover 322 on the lower panel 312 b. The mounting leg portions 325 are retained in the periphery of retaining holes 312 e of the lower panel 312 b. This lower panel 312 b is provided with a housing recess 312 c for housing the case 315. Moreover, these retaining holes 312 e are formed (see FIG. 40) in a flange portion 312 d which is formed at the periphery of the housing recess 312 c of the lower panel 312 b. On the root portion of the mounting leg portion 325, there are formed ribs 325 a. The ribs 325 a come, when the mounting leg portions 325 are retained in the retaining holes 312 e, into abutment against the flange portion 312 d of the lower panel 312 b to support the general portion 324. Here in the embodiment, three mounting leg portions 325 each are formed near the left and right edges of the general portion 324.

[0272] The inflator 337 is constructed into the cylinder type, in which its axial direction is arranged transversely of the vehicle, as shown in FIGS. 38 to 40. The inflator 337 is provided with the generally cylindrical body 338 and a bracket 339. The body 338 is provided with a cylindrical general portion 338 a and a reduced diameter portion 338 b protruding from the end face of the general portion 338 a. A plurality of gas discharge ports 338 c are arranged in the outer circumference of the reduced diameter portion 338 b. With the end face of the general portion 338 a apart from the reduced portion diameter 338 b, moreover, there is connected a connector 341 which is connected with a lead wire 342 for inputting an activating signal.

[0273] The bracket 339 is provided with a holding cylindrical portion 339 a formed of a sheet metal into a generally cylindrical shape for covering the body 338, and a plurality of (e.g., two in the embodiment) bolts 339 f protruded from the holding cylindrical portion 339 a. This holding cylindrical portion 339 a is provided on the side of its leading end with a bottom portion 339 b for covering the diametrically reduced portion 338 b of the body 338. The holding cylindrical portion 339 a is provided on the side of the other end face with an insert hole 339 c for holding the general portion 338 a of the body 338. In the holding cylindrical portion 339 a, there are formed a plurality of gas outflow ports 339 d for allowing the inflating gas discharged from the gas discharge ports 338 c of the body 338 to flow out. The gas outflow ports 339 d are opened in the vehicle rear side face of the holding cylinder portion 339 a, as mounted on the vehicle. On the holding cylindrical portion 339 a, moreover, there are arranged a plurality of clamping portions 339 e for holding the body 338. Each of the clamping portions 339 e is cut on its two sides in the axial directions of the holding cylindrical portion 339 a and is plastically deformed to bend into the holding cylindrical portion 339 a. Moreover, the body 338 is fixed in the holding cylindrical portion 339 a by inserting the body 338 from the insert hole 339 c with the diametrically reduced portion 338 b being ahead and by pushing the individual clamping portions 339 e further onto the outer circumferential side of the general portion 338 a.

[0274] This inflator 337 is fed, together with the not-shown airbag device mounted in the steering wheel 1, with the activating signal through the lead wire 342 when the airbag activating circuit mounted on the vehicle detects a front collision of the vehicle.

[0275] The airbag 26B used has constructions similar to those of the airbag 26 in the airbag device S1 of the first embodiment. Therefore, these constructions will not be explained and the same reference numbers will be used. In the lower side of the vehicle side wall portion 27 in the airbag 26B, there are formed through holes 27 g, 27 g and 27 h. The insert holes 27 g and 27 g are used to insert the individual bolts 339 f of the inflator 337. The insert hole 27 h is used to insert the body 338 of the inflator 37. Moreover, the airbag 26B is mounted in the case 315 by protruding the body 338 of the inflator 337 from the insert hole 27 h to clamp the periphery of each insert hole 27 g between the holding cylindrical portion 339 a and the bottom wall portion 318 of the case 315.

[0276] Here will be described how to assemble the airbag device S6. First of all, the airbag 26B is folded with the inflator 337 being housed therein. At this time, the inflator 337 is housed in the airbag 26B by protruding the individual bolts 339 f from the insert holes 27 g and by protruding the root portion side of the inflator body 338 from the insert hole 27 h. Moreover, the airbag 26B is folded up like the airbag 26 in the airbag device S1 of the first embodiment.

[0277] Then, the airbag 26B is wrapped, after being folded up, with the not-shown breakable wrapping film so that the airbag may not become loose. Here, the bolts 339 f of the inflator 337 protruded from the insert holes 27 g and the end portion of the body 338 protruded from the insert hole 27 h are also protruded from the wrapping film.

[0278] Next, the inflator 337 is housed together with the folded airbag 26B in the case 315 by protruding the individual bolts 339 f of the inflator 337 from the insert holes 318 a and by protruding the end portion of the inflator body 338 from the insert hole 316 e. When nuts 340 are then fastened on the individual bolts 339 f, the inflator 337 and the airbag 26B can be housed in the case 315 and mounted in the case 315.

[0279] The not-shown brackets of the case 315 are mounted on the dashboard reinforcement of the vehicle, on which an upper panel 312 a and the lower panel 312 b have already been mounted. The connector 341 having the lead wire 342 connected therewith is connected with the body 338 of the inflator 337. Next, the airbag cover 322 is pushed forward to insert and retain the individual mounting leg portions 325 in the retaining holes 312 e of the lower panel 312 b. Simultaneously with this, the hooks 317 of the case 315 are retained in the individual retaining holes 327 a and 328 a of the upper side wall portion 327 and the lower side wall portion 328 so that the airbag device S6 can be mounted on the vehicle.

[0280] If the activating signal is inputted through the lead wire 342 to the body 338 of the inflator 337 after the airbag device S6 is mounted on the vehicle, the inflating gas is discharged from the gas discharge ports 338 c of the inflator 337. Then, the inflating gas flows into the airbag 26B through the gas outflow ports 339 d of the bracket 339. Then, the airbag 26B expands and breaks the not-shown wrapping film, and pushes the door portion 334 of the airbag cover 322 to break the breakaway portion 331. Then, the airbag 26B opens the door portion 334 downward on the hinge portion 332 so that it extends and inflates upward along the column cover lower face 8 a, as indicated by double-dotted lines in FIGS. 38 and 41.

[0281] Moreover, the airbag device S6 of the sixth embodiment is constructed such that the extension promoting means for opening the door portion 334 quickly is arranged near the door portion 334 of the airbag cover 322. The extension promoting means is the guide wall portion 319 which is arranged along the door portion 334 for covering the lower side of the case opening 315 a. Near the area of upper end breakaway portion 331 a formed on the upper end 334 a side of the door portion 334, there is arranged the upper side wall portion 327 (or the mounting wall portion) serving as extension promoting means, which is mounted and fixed on the peripheral wall portion 316 by the hooks 317.

[0282] Therefore, the airbag 26B to be extended and expanded by feeding the inflating gas from the inflator 337 can be guided toward the upper end 334 a of the door portion 334 by the guide wall portion 319. As a result, the upper end breakaway portion 331 a arranged on the upper edge 334 a of the door portion 334 is broken at the beginning of the expansion of the airbag 26B by the protruding airbag 26B so that the door portion 334 can be smoothly opened downward from the upper end 334 a.

[0283] Moreover, the portion near the area of the upper end breakaway portion 331 a is firmly connected to the case 315 by the upper side wall portion 327 and the hooks 317 so that the area of the upper end breakaway portion 331 a is not moved relatively to the case 315 by the pushing force of the airbag 26B when the airbag 26B protrudes. By the airbag 26B, therefore, it is possible to break smoothly the upper end breakaway portion 331 a on the upper end 334 a side, or the opening starting side of the door portion 334. Then, the remaining breakaway portion 331 is broken smoothly.

[0284] As a result, in the airbag device S6 of the sixth embodiment, the door portion 334 can be quickly opened to protrude the airbag 26B quickly from the opening of the door portion 334 opened, thereby to extend and expand the airbag 26B.

[0285] In the airbag device S6 of the sixth embodiment, moreover, the door portion 334 can be opened with the largest opening size on the upper end 334 a side, because the door portion 334 opens downwardly. Specifically, the airbag 26B to protrude from the case 315 and to extend and expand is easily allowed to protrude upward from the largest opened portion on the upper end 334 a side of the door portion 334. By the opening action of the door portion 334, therefore, the airbag 26B can be guided toward the upper side so that it can be quickly extended and expanded toward the upper side.

[0286] In the airbag device S6 of the sixth embodiment, therefore, the airbag 26B can be quickly extended to protect the knees K of the driver MD as the passenger M properly.

[0287] In the airbag device S6 of the sixth embodiment, moreover, the airbag cover 322 is integrally molded to include the door portion 334 having the breakaway portion 331 arranged therearound, and the general portion 324 around the door portion 334. Therefore, the door portion 334 causes no disharmony with the surrounding general portion 324 so that its design is excellent.

[0288] In the airbag device S6 of the sixth embodiment, moreover, the upper end 334 a side which is the first side of the door portion 334 to open is arranged at a position on the vehicle rear side, or the side which is removed from the airbag 26B and the inflator 337. However, the guide wall portion and the upper side wall portion 327 near the upper end breakaway portion 331 a as the extension promoting means are arranged in the vicinity of the door portion 334 so that the door portion 334 can be quickly opened to extend and expand the airbag 26B quickly.

[0289] In the airbag device S6 of the sixth embodiment, moreover, the lower side of the door portion 334 in the airbag cover 322 is arranged on the vehicle front side so that a wide space can be retained in front of the knees K of the driver MD as the passenger M. Therefore, the airbag device S6 can be mounted on the vehicle without any interference with the toes or the like of the driver MD. If this point is not seen to be important, it is natural that the door portion 334 need not be inclined, arranging the upper end 334 a side more toward the vehicle rear and by arranging the hinge portion 332 more toward the vehicle front. For example, the door portion may be arranged in the vertical direction.

[0290] Next, the airbag device S7 of the seventh embodiment is shown in FIGS. 42 and 43. Here, the constructions of the airbag device S7 are similar other than a case 361 and an airbag cover 364 to those of the aforementioned airbag device S6. Therefore, the same members will not be explained and will be given the same reference number.

[0291] The case 361 used in the airbag device S7 is constructed not to have the aforementioned guide wall portion 319 formed in the case 315, and the remaining constructions are similar to those of the case 315. Therefore, the same members will not be explained and will be given the same reference number.

[0292] Here, the constructions of the airbag cover 364 are similar other than a door portion 366 are similar to those of the aforementioned airbag cover 322. Therefore, the same members will not be explained and will be given the same reference number.

[0293] The door portion 366 of the airbag cover 364 is provided, as shown in FIGS. 42 and 43, with a plurality of (e.g., five in the embodiment) ribs 367 of a generally triangular plate shape protruding forward. These individual ribs 367 are juxtaposed in the transverse direction of the vehicle. Moreover, the faces of the individual ribs 367 on the vehicle front side are easily pushed faces 367 a serving as extension promoting means. These easily pushed faces 367 a are arranged in the vertical directions and are pushed by the airbag 26B at the expanding time. On the other hand, the upper ends 367 b of the individual ribs 367 are arranged at positions near the upper end 366 a of the door portion 366 (or near the upper end breakaway portion 331 a), as shown in FIG. 42. These ribs 367 are pushed on their easily pushed faces 367 a backward at the beginning of the expansion of the airbag 26B by the protruding airbag 26B. As a result, the door portion 366, pushed at its easily pushed faces 367 a by the airbag 26B, is opened to be quickly broken the surrounding breakaway portion 331.

[0294] In the airbag device S7, too, the door portion 366 has the upper end 366 a arranged on the vehicle rear side and the hinge portion 332 arranged on the vehicle rear side. In other words, the door portion 366 is arranged at an inclination to intersect the vertical direction perpendicular to the longitudinal direction of the vehicle.

[0295] With this construction of the airbag device S7, at the beginning of the expansion of the airbag 26B, the protruding airbag 26B pushes the easily pushed faces 367 a of the ribs 367 backward to open the door portion 366. Normally in the case of a knee protecting airbag device having no rib arranged on the door portion, the protruding airbag pushes the vehicle front side face of the door portion to open the door portion. With the airbag device S7 having the aforementioned construction, however, the ribs 367 shorten the distance between the airbag 26B and the door portion 366 substantially. Therefore, the door portion 366 can be opened more quickly than that construction having no rib. As a result, the airbag 26B can be quickly protruded to extend and expand from the opening of the quickly opened door portion 366.

[0296] In the airbag device S7 of the seventh embodiment, moreover, the upper ends 367 b of the ribs 367 are arranged near the upper end breakaway portion 331 a. Therefore, the pushing force from the airbag 26B easily acts on the upper end breakaway portion 331 a so that the upper end breakaway portion 331 a can be smoothly broken by the protruding airbag 26B.

[0297] Here, the embodiment is constructed such that the plate-shaped ribs 367 are juxtaposed in the transverse directions of the vehicle. However, the shape and the number of arranged ribs should not be limited thereto. For example, the construction may be modified by arranging one rib which has a generally T-shaped section and an enlarged easily pushed face toward the front.

[0298] In the airbag device S7 of the seventh embodiment, too, the area of the upper end breakaway portion 331 a arranged on the upper end side of the door portion 366 is firmly connected to the case 315 by the upper side wall portion 327. When the airbag 26B protrudes, therefore, the area of the upper end breakaway portion 331 a is not moved relatively to the case 315 and the breakaway portion 331 a can be smoothly broken by the push of the airbag 26B. As a result, in the airbag device S7 of the embodiment, the door portion 366 can be quickly opened to extend the airbag 26B quickly.

[0299] Next, an airbag device S8 of an eighth embodiment is shown in FIG. 44. The constructions of this airbag device S8 are similar other than a case 370 and an airbag cover 373 to those of the aforementioned airbag device S6. Therefore, the same members will not be explained and will have the same reference numerals.

[0300] The case 370 is formed to have a generally trapezoidal shape in which the sectional shape in the transverse directions of the vehicle is set wider on the upper end side, as shown in FIG. 44. The door portion 374 of the airbag cover 373 is formed into the generally trapezoidal shape which is made wider on its upper end side according to the shape of a case opening 370 a.

[0301] In the airbag device S8, more specifically, a left side wall portion 371 and a right side wall portion 372 of the case 370 are inclined upward apart from each other. In other words, the left side wall portion 371 and the right side wall portion 372 are inclined each other so that the upper side distance between the left side wall 371 portion and the right side wall portion 372 is set longer than the lower side distance between the left side wall portion 371 and the right side wall portion 372.

[0302] With this construction of the airbag device S8, the inflating gas discharged from the inflator is guided upward in the airbag 26B by the left side wall portion 371 and the right side wall portion 372 of the case 370. In other words, the airbag 26B to be extended and expanded by introducing the inflating gas from the inflator can be guided toward the upper end 371 a of the door portion 374. With the protruding of the airbag 26B, therefore, the door portion 374 to open downward can be smoothly opened from its upper end 374 a side. As a result, the airbag 26B can be quickly protruded to extend and expand from the quickly opened opening of the door portion.

[0303] Here, the sixth to eighth embodiments have been described by exemplifying the airbag devices S6 to S8 arranged on the vehicle front side of the driver MD so as to protect the knees of the driver MD. As shown in FIG. 45, however, the airbag device S6 may be arranged in front of the passenger MP seated on the passenger's seat so as to protect the knees of the seated passenger MP.

[0304] Here will be described knee protecting airbag devices S9 to S11 capable of achieving the fifth object of the invention.

[0305] Here, the constructions of a vehicle for mounting the knee protecting airbag device S9 of the ninth embodiment are similar to those of the aforementioned airbag device S1 of the first embodiment. Therefore, the common members will be omitted on their description by designating them by the common reference numerals.

[0306] The knee protecting airbag device S9 of the ninth embodiment is shown in FIGS. 46 to 48. The airbag device S9 comprises a folded airbag 26C, an inflator 421, a case 419 for housing the airbag 26C and the inflator 421, and an airbag cover 412 for covering the folded airbag 26C. Moreover, the airbag device S9 is so mounted on the holding member 12 that the case 419 is arranged to the front of the plate-shaped holding member 12. The constructions of this holding member 12 are similar to those of the holding member 12 in the airbag device S1 of the first embodiment.

[0307] In the case of the embodiment, the case 419 is made of a sheet metal. This case 419 comprises, as shown in FIGS. 46 to 48, a peripheral wall portion 419 a of a generally rectangular tubular shape and a bottom wall portion 419 b of a generally rectangular shape. The bottom wall portion 419 b closes the vehicle front side of the peripheral wall portion 419 a. On the periphery of the opening 419 c on the vehicle rear side of the peripheral wall portion 419 a, there is formed a flange portion 419 d which protrudes outward for mounting the case 419 on the holding member 12. In the embodiment, moreover, the case 419 is mounted and fixed on the holding member 12 by means of the not-shown bolts or the like using the flange portion 419 d, as shown in FIGS. 46 to 49. As shown in FIG. 46, moreover, the case 419 is arranged to protrude the airbag 26C along the lower face 8 a of the column cover 8 when the housed airbag 26C protrudes from the case 419. In other words, the case 419 is so arranged that the axial directions 0 of the peripheral wall portion 419 a may extend along the lower face 8 a of the column cover 8 (or along the axial directions of the steering column 3).

[0308] In the upper side wall portion 419 e of the peripheral wall portion 419 a, moreover, there are formed mounting holes 419 f, as shown in FIGS. 46 to 48. These mounting holes 419 f are arranged to mount the inflator 421 in the case 419 by inserting the later-described bolts 423 b of the inflator 421. The case 419 mounts and fixes the inflator 421 on the upper side wall portion 419 e of the peripheral wall portion 419 a, as shown in FIGS. 46 to 48. Moreover, the folded airbag 26C is housed in the case 419 on the left and right sides of the inflator 421.

[0309] As shown in FIGS. 46 to 48, 50 and 51, the inflator 421 is of the cylinder type which can discharge the inflating gas G in response to the electric signal. The inflator 421 is provided with a generally cylindrical body 422 and two bracket portions 423 and 423. Moreover, the inflator 421 is so arranged in the case 419 that its axial direction CO is substantially parallel to the axial direction O of the peripheral wall portion 419 a of the case 419.

[0310] In the body 422, a plurality of gas discharge ports 422 a for discharging the inflating gas are arranged at the front end side. In the case of the embodiment, the body 422 is activated simultaneously with the airbag device for the steering wheel by the electric signal coming from the control device for activating the not-shown airbag device which is mounted on the steering wheel 1. Each of the bracket portions 423 comprises a retaining ring 423 a made of a sheet metal, and the bolt 323 b protruding from the retaining ring 423 a. This retaining ring 423 a is plastically deformable to have such a reduced diameter that it can clamp the body 422. The inflator 421 is mounted and fixed on the case 419 in the following manner. Specifically, the body 422 assembled the bracket portions 423 and 423 is arranged in the airbag 26C, and the bolts 423 b and 423 b are protruded from the airbag 26C. Then, these bolts 423 b and 423 b are inserted into the mounting holes 419 f and 419 f of the case 419 and are fastened to the case 419 by means of nuts 424 and 424. Moreover, the not-shown lead wire is connected with the body 422.

[0311] In the case of the embodiment, moreover, the airbag cover 412 is mounted and fixed on the vehicle rear side face of the holding member 12, as shown in FIGS. 46 to 49. Moreover, the airbag cover 412 also plays the role of the interior decorative portion to cover the vehicle rear side of the folded airbag 26C and to cover the face of the holding member 12 on the interior side. In the airbag cover 412, there is formed a door portion 414 of a generally rectangular plate shape, which is located at the arranged position of the opening 419 c of the case 419. The door portion 414 is pushed by the extending and expanding airbag 26C and opened into the vehicle. Around this door portion 414, there are arranged a thinned breakaway portion 413 having an inverted U-shape, as viewed from the interior side, and a hinge portion 415 having an integral hinge on the lower edge. The door portion 414 is pushed by the extending and expanding airbag 26C to break the breakaway portion 413 and opened downward to the interior side.

[0312] The airbag 26C used has constructions similar to those of the airbag 26 in the airbag device S1 of the first embodiment. Therefore, the same members will not be explained and will be given the same reference number. In the lower side of the vehicle side wall portion 27 in the airbag 26C, there are formed insert holes 27 i and 27 i for inserting the individual bolts 423 b of the inflator 421 thereinto. In the airbag 26C, moreover, two tethers 32A and 32A on the lower side are arranged on the left and right sides of the inflator 421 (see FIGS. 50 and 51).

[0313] Here will be described how to mount the airbag device S9 on the vehicle. First of all, the airbag 26C is folded while housing the inflator 421 therein. At this time, the individual bolts 423 b of the inflator 421 are protruded from the individual insert holes 27 i formed in the airbag 26C. Moreover, the not-shown lead wire extending from the body 422 is extended from the predetermined not-shown insert hole in the airbag 26C. Moreover, the airbag 26C is wrapped, after folded up, with the not-shown breakable wrapping film. The individual bolts 423 b are protruded from the wrapping film and are assembled with the not-shown thinned spring nuts.

[0314] Next, the folded airbag 26C is inserted together with the inflator 421 into the case 419, and the individual bolts 423 b are protruded out of the case 419 through the individual mounting holes 419 f of the case 419. By fastening the individual protruded bolts 423 b on the case 419 by using the nuts 424, the folded airbag 26C and the inflator 421 are housed in the case 419. Moreover, the not-shown lead wire extending from the inflator body 422 is led from the wrapping film and from the not-shown insert hole of the case 419.

[0315] Then, the case 419 is mounted and fixed on the holding member 12 by using the flange portion 419 d to form the airbag assembly. The mounting portions 12 a and 12 a on the two transverse ends of the holding member 12 mounted the airbag cover 412 are individually fixed by means of the bolts on the frame portions FC and FR of the vehicle, which are arranged on the left and right side. Then, the not-shown lead wire is connected with the control circuit, and the dashboard 10 and so on is mounted on the vehicle. As a result, the airbag device S9 can be mounted on the vehicle, as shown in FIGS. 46 to 49.

[0316] When the predetermined electric signal is inputted to the inflator body 422 after the airbag device S9 was mounted on the vehicle, the inflating gas G is discharged from the gas discharge ports 422 a to expand the airbag 26C, as shown in FIG. 50. Then, the airbag 26C breaks the not-shown wrapping film and pushes and opens the door portion 414 of the airbag cover 412 so that the airbag 26C extends and expands upward from the communication hole 12 b along the column cover lower face 8 a.

[0317] In the airbag device S9 of the ninth embodiment, the inflator 421 of the cylinder type is arranged in its axial direction CO in parallel with the axial direction O of the peripheral wall portion 419 a of the case 419. Specifically, the inflator 421 of the cylinder type is made longer in the axial length w1 than the external diameter D1, as shown in FIGS. 47 and 48. In the airbag device S9, therefore, the vertical and transverse widths w2 and w3 perpendicular to the axis O of the case 419 can be set as following. The widths w2 and w3 of the case 419 can be set the sizes which are calculated by adding the housing space of the airbag 26C to the external diameter D1 of the inflator 421. In other words, the widths w2 and w3 of the case 419 can be made smaller than those of the case in which the inflator 421 is arranged with its axial direction CO being generally perpendicular to the axial directions O of the case peripheral wall portion 419 a.

[0318] Therefore, the airbag device S9 of the ninth embodiment can be arranged in a narrow housing space by reducing the widths w2 and w3 perpendicular to the axis O of the case 419.

[0319] Here will be described an airbag device S10 of a tenth embodiment. The airbag device S10 is constructed, as shown in FIG. 52, to use a disc type inflator 435 as the inflator. The constructions of the airbag device S10 are similar other than the inflator 435 and a case 432 to those of the aforementioned airbag device S9. Therefore, the same members will not be explained and will have the same reference numbers.

[0320] The airbag device S10 comprises a folded airbag 26D, the disc type inflator 435, and the case 432 for housing the airbag 26D and the inflator 435. Moreover, the airbag device S10 is mounted like the aforementioned airbag device S9 on the holding member 12 by arranging the case 432 on the front side of the holding member 12.

[0321] The case 432 comprises, as shown in FIGS. 52 to 54, a peripheral wall portion 432 a of a generally rectangular tubular shape, and a bottom wall portion 432 b of a generally rectangular shape. The bottom wall portion 432 b closes the vehicle front side of the peripheral wall portion 432 a. From the periphery of an opening 432 c of the peripheral wall portion 432 a on the vehicle rear side, as in the aforementioned case 419, there is protruded outward a flange portion 432 d for mounting the case 432 on the holding member 12. In an upper sidewall portion 432 e in the peripheral wall portion 432 a, as shown in FIGS. 52 to 54, there are formed an insert hole 432 f and four mounting holes 432 g. The insert hole 432 f is arranged to hold the later-described body 435 a of the inflator 435. The individual mounting holes 432 g are arranged to pass four bolts 438 for mounting the inflator 435 on the case 432. As shown in FIGS. 52 to 54, the case 432 mounts and fixes the inflator 435 on its upper side wall portion 432 e of the peripheral wall portion 432 a. Then, the folded airbag 26D is housed below the inflator 435 in the case 432.

[0322] Moreover, the case 432 is formed such that the opening 432 c of the peripheral wall portion 432 a on the vehicle rear side is positioned closer at its upper end 432 i to the vehicle rear than its lower end 432 j (see FIG. 52). In other words, at the peripheral wall portion 432 a, the rear end side of the upper side wall portion 432 e is positioned closer to the vehicle rear side than the rear end side of the lower side wall portion 432 h.

[0323] The inflator 435 is of the disc type, as shown in FIGS. 52 to 54. This inflator 435 includes the generally cylindrical body 435 a capable of discharging the inflating gas G in response to the electric signal, and a generally square annular flange portion 435 b protruding from the outer circumference of the body 435 a. In the end portion of the lower side of the body 435 a, there are formed a plurality of gas discharge ports 435 c. In the flange portion 435 b, there are formed four insert holes 435 d for passing the bolts 438 formed on a retainer 437 arranged in the airbag 26D. Moreover, the body 435 a is connected with a not-shown lead wire.

[0324] The inflator 435 and the airbag 26D are mounted and fixed in the case 432 by using the generally square annular retainer 437 which is arranged in the airbag 26D. Specifically, the individual bolts 438 of the retainer 437 are inserted, as shown in FIG. 54, into the later-described insert holes 27 j of the airbag 26D, the mounting holes 432 g of the case 432 and the insert holes 435 d formed in the flange portion 435 b of the inflator 435 and are individually fastened by nuts 439. Thus, the inflator 435 and the airbag 26D are mounted and fixed on the upper side wall portion 432 e of the case 432. Then, the inflator 435 is so mounted and fixed on the upper side wall portion 432 e (or the peripheral wall portion 432 a) of the case 432 that its axial direction DO is generally perpendicular to the axial direction O of the case peripheral wall portion 432 a, as shown in FIG. 52.

[0325] The airbag 26D has a construction similar to that of the airbag 26C. In the lower side of the vehicle side wall portion 27 in the airbag 26D, moreover, there are formed the insert holes 27 j for inserting the individual bolts 438 of the retainer 437, and an insert hole 27 k opened circularly for holding the main body 435 a of the inflator 435.

[0326] In the airbag device S10, as described above, the disc type inflator 435 is so mounted and fixed on the upper side wall portion 432 e (or the peripheral wall portion 432 a) of the case 432 that its axial direction DO may be generally perpendicular to the axial direction O of the case peripheral wall portion 432 a. Moreover, the disc type inflator 435 is made larger in the external diameter D2 including the retainer 437 than in the length (or the thickness) w4 in the axial direction DO, as shown in FIG. 52. In the airbag device S10, therefore, the distance from the upper side wall portion 432 e (the wall portion mounted the inflator 435) to the lower side wall portion 432 h (the wall portion confronting the inflator 435), that is, the vertical width w5 of the case 432 perpendicular to the axis O of the peripheral wall portion 432 a can be set as follows. The width w5 of the case 432 can be set the size which is calculated by adding the housing space of the airbag 26D to the length size (or the thickness size) w4 of the inflator 435. As a result, the width w5 of the case 432 can be made smaller than that of the case in which the inflator 435 is mounted and fixed on the bottom wall portion 432 b of the case 432 so that the axial direction DO is parallel to the axial directions of the case peripheral wall portion 432 a.

[0327] Therefore, the airbag device S10 of the tenth embodiment can be arranged in a narrow housing space by reducing the width w5 in the directions perpendicular to the axis of the case 432.

[0328] In the airbag device S10 of the tenth embodiment, moreover, the inflator 435 is mounted and fixed on the upper side wall portion 432 e of the case 432. This upper side wall portion 432 e is positioned on its rear end side closer to the vehicle rear side than the rear end side of the lower side wall portion 432 h. In other words, the upper side wall portion 432 e can be made longer in the longitudinal direction than the remaining peripheral wall portion 432 a (i.e., the lower side wall portion 432 h) in the case 432. Compared with the case in which the inflator 435 is mounted and fixed on the lower wall portion 432 a, therefore, the depth of the case 432 is reduced. Of course if this point is not given importance it is possible that the inflator 435 may be mounted and fixed on the lower side wall portion 432 h. The inflator 435 may naturally be arranged on the left and right side wall portions of the case peripheral wall portion 432 a. When the inflator 435 is arranged on the left and right side wall portions of the peripheral wall portion 432 a, it is possible to reduce the width w6 (see FIG. 54) in the transverse directions which are the perpendicular directions to the axis of the case peripheral wall portion 432 a.

[0329] Here will be described an airbag device S11 of an eleventh embodiment. This airbag device S11 is constructed, as shown in FIG. 57, such that a cylinder type inflator 445 is arranged outside of a case 442 and provided with a gas feed passage 446 for feeding the inflating gas to an airbag 26E folded and housed in the case 442. Moreover, the constructions of the airbag device S11 are similar to those of the aforementioned airbag devices S9 and S10 excepting the inflator 445, the gas feed passage 446 and the case 442. Therefore, the same members will not be explained and will be given the same reference numerals.

[0330] The case 442 is provided, as shown in FIGS. 58 and 59, with a peripheral wall portion 442 a of a generally rectangular tubular shape, and a bottom wall portion 442 b of a generally rectangular shape for closing the vehicle front side of the peripheral wall portion 442 a. From the periphery of an opening 442 c of the peripheral wall portion 442 a on the vehicle rear side, moreover, there is protruded outward a flange portion 442 d for mounting the case 442 on the holding member 12. In the bottom wall portion 442 b of the case 442, as shown in FIG. 58, there is formed an insert hole 442 e for the gas feed passage 446. As shown in FIGS. 58 and 59, in the case 442, the later-described end portion 446 b of the gas feed passage 446 is arranged near a lower side wall portion 442 f of the peripheral wall portion 442 a and generally in parallel with the axial direction O of the case peripheral wall portion 442 a. Moreover, the folded airbag 26E is housed on the left and right sides of the gas feed passage 446 in the case 442.

[0331] The gas feed passage 446 is constructed, as shown in FIG. 57, into a pipe shape to connect its one end 446 a to the inflator 445 and its other end portion 446 b to the airbag 26E folded and housed in the case 442. The inflator 445 is mounted and fixed on a frame FF such as a floor panel on the vehicle front side of the case 442. The end portion 446 b of the gas feed passage 446 is inserted, as shown in FIG. 58, into the airbag 26E through the insert hole 442 e formed in the case 442 and an insert hole 26 d formed in the airbag 26E. In the end portion 446 b of the gas feed passage 446, there are axially formed a plurality of gas discharge ports 446 c for introducing the inflating gas G into the airbag 26E. The airbag 26E and the gas feed passage 446 are connected and fixed by a clamp 447, as shown in FIG. 58.

[0332] With this construction of the airbag device S11, the inflator 445 is not arranged in the case 442, in which there are arranged only the folded airbag 26E and the gas feed passage 446 for feeding the inflating gas G to the airbag 26E. This gas feed passage 446 need not be provided with a gas producing mechanism but may pass the inflating gas G, so that it can have a smaller volume than that of the inflator 445. For example, as shown in FIG. 59, the gas feed passage 446 of the embodiment can be given a smaller external diameter D3 than that of the cylinder type inflator. As compared with the airbag device S9 having the cylinder type inflator 421 arranged in the case 419, therefore, the vertical and transverse widths w7 and w8 perpendicular to the axis of the case peripheral wall portion 442 a can be made smaller.

[0333] In the airbag device S11 of the eleventh embodiment, therefore, the case 442 can be arranged in the narrow housing space by reducing the widths w7 and w8 perpendicular to the axis of the case 442.

[0334] In the airbag device S11 of the eleventh embodiment, moreover, an intermediate portion 446 d of the gas feed passage 446 between the end portions 446 a and 446 b may be bent and arranged without any interference with the members arranged around the airbag device S11. Therefore, the intermediate portion 446 d of the gas feed passage 446 can be easily arranged in the narrow space.

[0335] When the inflator 445 acts in this airbag device S11, the inflating gas G is discharged from the inflator 445 via the gas feed passage 446 and the gas discharge ports 446 c into the airbag 26E. Then, the expanding airbag 26E extends and expands while pushing and opening the door portion 414 of the airbag cover 412.

[0336] In case the inflator 445 is to be arranged at a position different from that of the case 442, on the other hand, an airbag device S12 may be constructed, as shown in FIGS. 60 to 62, such that the end portion 446 b of the gas feed passage 446 is arranged in the case 442 and generally perpendicularly of the axial direction O of the case peripheral wall portion 442 a. The constructions of the airbag device S12 are similar to those of the aforementioned airbag device S11, excepting that the end portion 446 b of the gas feed passage 446 is arranged in the case 442 and generally perpendicularly of the axial direction O of the case peripheral wall portion 442 a. Therefore, the same members will not be explained and will be given the same reference numerals.

[0337] In the airbag device S12, on the other hand, the insert hole 442 e for holding the gas feed passage 446 is formed in the case peripheral wall portion 442 a, as shown in FIG. 62. In the case 442, moreover, the gas feed passage 446 is so arranged near the bottom wall portion 442 b and along the transverse directions as to intersect the axial direction O of the case peripheral wall portion 442 a generally perpendicularly. Moreover, the folded airbag 26E is housed on the vehicle rear side of the gas feed passage 446 in the case 442.

[0338] With this construction of the airbag device S12, the gas feed passage 446 is given the smaller external diameter D3 than that of the cylinder type inflator. Therefore, the vertical width w9 in the directions perpendicular to the axis O of the case peripheral wall portion 442 a can be made smaller than that of the case, in which the inflator 421 used in the aforementioned airbag device S9 of the ninth embodiment is so axially arranged like the airbag device S12 in the directions generally perpendicular to the axial directions O of the case peripheral wall portion 419 a. With this construction, moreover, it is possible to reduce the depth w10 of the case 442 toward the vehicle front side, too.

[0339] Here in the individual airbag devices S9 to S12, the cases 419, 432 and 442 are made separate of the holding member 12. However, the cases 419, 432 and 442 may be formed integrally with the holding member 12 by the pressing or welding method using a metallic material such as a sheet metal or by the die-casting method using a light metal alloy material of aluminum or the like.

[0340] In the individual airbag devices S9 to S12, moreover, the cases 419, 432 and 442 are held by the holding member 12. However, the cases 419, 432 and 442 may be held by a portion within the column cover 8 by attaching brackets or the like on a portion of the column tube 5 in the steering column 3 which does not move. In an alternative case in which the lower panel of the dashboard 10 is arranged below the column cover 8, the cases 419, 432 and 442 may be housed and arranged in the lower panel. 

What is claimed is:
 1. A knee protecting airbag device comprising: a folded airbag; an inflator for feeding an inflating gas to said airbag; and a case housing said airbag and said inflator and arranged in front of a seated passenger, wherein said airbag fed with the inflating gas extends and expands, while protruding to the rear from the opening of said case, to protect the knees of the passenger, wherein said knee protecting airbag device further comprises a holding member holding said case, which has a mounting portion for mounting on the vehicle, and wherein said holding member includes a communication hole communicating with the opening of said case for allowing said airbag to protrude when expanding, and a support face arranged on the periphery of said communication hole for supporting the vehicle front side face of said expanding airbag.
 2. A knee protecting airbag device according to claim 1, wherein said case having housed said folded airbag and said inflator is assembled in advance with said holding member into an assembly.
 3. A knee protecting airbag device, wherein a knee protecting folded airbag and an inflator for feeding an inflating gas to said airbag are housed in a plate-shaped holding member arranged in front of the knees of a seated passenger, wherein an airbag cover for covering the housed airbag in a manner allowing the airbag to protrude is mounted on said holding member, wherein said holding member includes a bottomed box-shaped housing portion for housing said airbag and said inflator, wherein said housing portion is opened toward the vehicle rear, wherein said airbag cover includes: a door portion for covering the opening of said housing portion, to open when pushed by said expanding airbag; a thinned breakaway portion arranged periphery of said door portion broken for said door portion to open; a hinge portion arranged around said door portion for providing a pivot for said door portion being opened; and a general portion arranged around said door portion, said breakaway portion and said hinge portion for covering the periphery of said housing portion in said holding member on the vehicle rear side, and wherein mounting members to be mounted on said housing portion through said holding member are arranged at a plurality of portions of said general portion in the opening periphery of said housing portion.
 4. A knee protecting airbag device according to claim 3, wherein the individual mounting members of said airbag cover have retaining holes, and wherein said housing portion has a plurality of hooks to be inserted into said retaining holes for retaining said mounting members.
 5. A knee protecting airbag device according to claim 3, wherein said holding member has a joining portion which is connected to the vehicle body side when said knee protecting airbag device is mounted on the vehicle, and wherein a kinetic energy absorbing member capable of absorbing the kinetic energy of the knees is arranged on the body side of said vehicle, to which said joining portion is connected.
 6. A knee protecting airbag device comprising an airbag module arranged in front of the knees of a seated passenger, wherein said airbag module includes: a knee protecting folded airbag; an inflator capable of feeding an inflating gas to said airbag; a case for housing said airbag and said inflator; and an airbag cover for covering the vehicle rear side in the opening of said case, wherein said case has an opening for allowing said airbag when extending and expanding to protrude toward the rear of the vehicle, wherein said knee protecting airbag device further includes a plate-shaped holding member made of a deformable material, wherein said holding member has a plate-shaped portion extending from around the opening of said case, and mounting portions to be mounted on the vehicle body, wherein said plate-shaped portion is arranged on the vehicle front side of the area of said airbag which has completed its expansion and, wherein said mounting portions are arranged near the periphery of said plate-shaped portion, wherein said holding member is constructed to hold the case having housed said airbag and said inflator, and said airbag cover, and wherein when a kinetic energy higher than a predetermined level is applied by said knees to said airbag, said plate-shaped portion can be deformed to absorb the kinetic energy of said knees.
 7. A knee protecting airbag device according to claim 6, wherein said plate-shaped portion of said holding member has ribs capable of adjusting the quantity of the kinetic energy of said knees which can absorbed.
 8. A knee protecting airbag device according to claim 7, wherein said plate-shaped portion of said holding member has a flange portion arranged on its periphery for adjusting the quantity of the kinetic energy of said knees which can absorbed.
 9. A knee protecting airbag device arranged in front of the knees of a seated passenger and comprising: a knee protecting folded airbag; an inflator for feeding an inflating gas to said airbag; a case opened toward the vehicle rear for housing said airbag and said inflator; and an airbag cover for covering said case on the rear-facing side, wherein said airbag cover consists of an integral molding including: a door portion for covering the opening of said case and a general portion arranged around said door portion, wherein said door portion includes: a hinge portion arranged at a lower end for providing a pivot when said door portion is opened; and a thinned breakaway portion arranged at the periphery excepting said hinge portion, that can be opened downward when said airbag expands, and wherein extension promoting means for opening said door portion quickly to promote the extension and expansion of said airbag is arranged near said door portion.
 10. A knee protecting airbag device according to claim 9, wherein said door portion is arranged at such an inclination as to intersect the vertical direction by arranging its upper end toward the vehicle rear and its hinge portion toward the vehicle front.
 11. A knee protecting airbag device according to claim 10, wherein said case includes a peripheral wall portion and a bottom wall portion, wherein said airbag cover has a mounting wall portions for mounting and fixing said airbag cover on said case periphery wall portion, and wherein said wall mounting portion serving as said extension promoting means is arranged near an upper end breakaway portion above said door portion.
 12. A knee protecting airbag device according to claim 10, wherein a guide wall portion covering the lower side of said opening is arranged in said case near said door portion, and wherein said guide wall portion serves as said extension promoting means to guide said expanding airbag toward the upper side of said door portion.
 13. A knee protecting airbag device according to claim 10, wherein said door portion has ribs formed to protrude forward, and wherein the face of said ribs on the vehicle front side is an easily pushed face serving as said extension promoting means for opening said door portion when pushed by said expanding airbag.
 14. A knee protecting airbag device according to claim 10, wherein said case includes a peripheral wall portion and a bottom wall portion, wherein a left side wall portion and a right side wall portion of said peripheral wall portion are inclined each other so that the upper side distance between said left side wall portion and said right side wall portion is set longer than the lower side distance between said left side wall portion and said right side wall portion, and wherein said left side wall portion and said right side wall portion act as said extension promoting means.
 15. A knee protecting airbag device comprising: a folded airbag; an inflator for feeding an inflating gas to said airbag; and a case housing said airbag and said inflator and arranged below a steering column, wherein said airbag fed with the inflating gas extends and expands, while protruding toward the rear of the vehicle from the opening of said case, to protect the knees of the passenger, wherein said case is opened toward the vehicle rear side and includes a peripheral wall portion and a bottom wall portion closing the vehicle front side of said peripheral wall portion, and wherein said inflator is of a cylinder type and is so housed in said case that its axial direction is generally parallel to the axial direction of said case peripheral wall portion.
 16. A knee protecting airbag device comprising: a folded airbag; an inflator for feeding an inflating gas to said airbag; and a case housing said airbag and said inflator and arranged below a steering column, wherein when said airbag fed with the inflating gas extends and expands it protrudes to the rear of the vehicle from the opening of said case, to protect the knees of the passenger, wherein said case is opened on the vehicle rear side and includes a peripheral wall portion and a bottom wall portion closing the vehicle front side of said peripheral wall portion, and wherein said inflator is of a disc type and is so mounted and fixed on the peripheral wall portion of said case that its axial direction is generally perpendicular to the axial direction of said case peripheral wall portion.
 17. A knee protecting airbag device according to claim 16, wherein said case is constructed such that the upper side of the opening is positioned closer to the vehicle rear side than the lower side of the opening, and wherein said inflator is mounted and fixed on the upper side wall portion in said case peripheral wall portion.
 18. A knee protecting airbag device comprising: a folded airbag; an inflator for feeding an inflating gas to said airbag; and a case housing said airbag and arranged below a steering column, wherein when said airbag fed with the inflating gas extends and expands, it protrudes backward of the vehicle from the opening of said case, to protect the knees of the passenger, wherein said case is opened toward the vehicle rear side and includes a peripheral wall portion and a bottom wall portion closing the vehicle front side of said peripheral wall portion, and wherein said inflator has a gas feed passage for feeding the inflating gas to said airbag folded and housed in said case, the inflator being arranged outside of said case. 